plucky (1) fetchmail.1.gz

Provided by: fetchmail_6.4.39-1_amd64 bug

NAME

       fetchmail - fetch mail from a POP, IMAP, ETRN, or ODMR-capable server

SYNOPSIS

       fetchmail [option...] [mailserver...]
       fetchmailconf

DESCRIPTION

       fetchmail  is  a  mail-retrieval  and  forwarding  utility;  it fetches mail from remote mail servers and
       forwards it to your local (client) machine's delivery system.  You can then  handle  the  retrieved  mail
       using  normal mail user agents such as mutt(1), elm(1) or Mail(1).  The fetchmail utility can be run in a
       daemon mode to repeatedly poll one or more systems at a specified interval.

       The fetchmail program can gather mail from servers supporting any of the common mail-retrieval protocols:
       POP2  (legacy, to be removed from future release), POP3, IMAP2bis, IMAP4, and IMAP4rev1.  It can also use
       the ESMTP ETRN extension and ODMR.  (The RFCs describing all these protocols are listed  at  the  end  of
       this manual page.)

       While  fetchmail  is  primarily  intended  to  be  used  over on-demand TCP/IP links (such as SLIP or PPP
       connections), it may also be useful as a message transfer agent  for  sites  which  refuse  for  security
       reasons to permit (sender-initiated) SMTP transactions with sendmail.

SUPPORT, TROUBLESHOOTING

       For  troubleshooting,  tracing  and debugging, you need to increase fetchmail's verbosity to actually see
       what happens. To do that, please run both of the two following commands, adding all of the options  you'd
       normally use.

              env LC_ALL=C fetchmail -V -v --nodetach --nosyslog

              (This command line prints in English how fetchmail understands your configuration.)

              env LC_ALL=C fetchmail -vvv  --nodetach --nosyslog

              (This command line actually runs fetchmail with verbose English output.)

       Also see item #G3 in fetchmail's FAQ ⟨https://fetchmail.sourceforge.io/fetchmail-FAQ.html#G3⟩.

       You  can omit the LC_ALL=C part above if you want output in the local language (if supported). However if
       you are posting to mailing lists, please leave it in. The maintainers do not necessarily understand  your
       language, please use English.

TLS (SSL) QUICKSTART

       Your  fetchmail  distribution  should  have come with a README.SSL file, which see.  It is recommended to
       configure all polls with --ssl --sslproto tls1.2+ if supported by the server, which configures  fetchmail
       along recent IETF proposed standards and best current practices, RFC-8314, RFC-8996, RFC-8997.

CONCEPTS

       If  fetchmail  is  used  with a POP or an IMAP server (but not with ETRN or ODMR), it has two fundamental
       modes of operation for each user account from which it retrieves mail: singledrop- and multidrop-mode.

       In singledrop-mode,
              fetchmail assumes that all messages in the user's account (mailbox)  are  intended  for  a  single
              recipient.   The  identity  of  the  recipient  will  either  default  to the local user currently
              executing fetchmail, or will need to be explicitly specified in the configuration file.

              fetchmail uses singledrop-mode when the fetchmailrc configuration contains at most a single  local
              user specification for a given server account.

       In multidrop-mode,
              fetchmail  assumes  that the mail server account actually contains mail intended for any number of
              different recipients.  Therefore, fetchmail must attempt to deduce the proper "envelope recipient"
              from  the  mail  headers of each message.  In this mode of operation, fetchmail almost resembles a
              mail transfer agent (MTA).

              Note that neither the POP nor IMAP protocols were intended for use  in  this  fashion,  and  hence
              envelope  information is often not directly available. The ISP must store the envelope information
              in some message header and. The ISP must also store one copy of  the  message  per  recipient.  If
              either of the conditions is not fulfilled, this process is unreliable, because fetchmail must then
              resort to guessing the true envelope recipient(s) of a message. This  usually  fails  for  mailing
              list messages and Bcc:d mail, or mail for multiple recipients in your domain.

              fetchmail  uses  multidrop-mode when more than one local user and/or a wildcard is specified for a
              particular server account in the configuration file.

       In ETRN and ODMR modes,
              these considerations do not apply, as these protocols are based on SMTP, which  provides  explicit
              envelope recipient information. These protocols always support multiple recipients.

       As  each  message  is  retrieved, fetchmail normally delivers it via SMTP to port 25 on the machine it is
       running on (localhost), just as though it were being passed in over  a  normal  TCP/IP  link.   fetchmail
       provides the SMTP server with an envelope recipient derived in the manner described previously.  The mail
       will then be delivered according to your MTA's rules (the Mail Transfer  Agent  is  usually  sendmail(8),
       exim(8),  or postfix(8)).  Invoking your system's MDA (Mail Delivery Agent) is the duty of your MTA.  All
       the delivery-control mechanisms (such as .forward files) normally available through your system  MTA  and
       local delivery agents will therefore be applied as usual.

       If your fetchmail configuration sets a local MDA (see the --mda option), it will be used directly instead
       of talking SMTP to port 25.

       If the program fetchmailconf is available, it will assist you in setting up  and  editing  a  fetchmailrc
       configuration.   It  runs  under  the  X  window  system and requires that the language Python and the Tk
       toolkit (with Python bindings) be present on your system.  If you are  first  setting  up  fetchmail  for
       single-user  mode,  it is recommended that you use Novice mode.  Expert mode provides complete control of
       fetchmail configuration, including the multidrop features.  In either case, the 'Autoprobe'  button  will
       tell  you the most capable protocol a given mail server supports, and warn you of potential problems with
       that server.

PREFACE ON THIS MANUAL

       Fetchmail's run-time strings have been translated (localized) to some languages, but the manual  is  only
       available  in  English.   In some situations, for comparing output to manual, it may be helpful to switch
       fetchmail to English output by overriding the locale variables, for instance:

              env LC_ALL=C fetchmail # add other options before the hash

              env LANG=en fetchmail # other options before the hash

       or similar. Details vary by operating system.

GENERAL OPERATION

       The behavior of fetchmail is controlled by command-line options and a run control  file,  ~/.fetchmailrc,
       the  syntax  of which we describe in a later section (this file is what the fetchmailconf program edits).
       Command-line options override ~/.fetchmailrc declarations.

       Each server name that you specify following the options on the command line will be queried.  If  you  do
       not  specify  any  servers  on  the  command  line, each 'poll' entry in your ~/.fetchmailrc file will be
       queried, unless the idle option is used, which see.

       To facilitate the use of fetchmail in scripts and pipelines, it returns an  appropriate  exit  code  upon
       termination -- see EXIT CODES below.

       The  following  options modify the behavior of fetchmail.  It is seldom necessary to specify any of these
       once you have a working .fetchmailrc file set up.

       Almost all options have a corresponding keyword which can be used to declare them in a .fetchmailrc file.

       Some special options are not covered here, but are documented instead in sections on  AUTHENTICATION  and
       DAEMON MODE which follow.

   General Options
       -? | --help
              Displays option help.

       -V | --version
              Displays  the  version  information  for  your  copy  of  fetchmail.   No mail fetch is performed.
              Instead, for each server specified, all the option information that would be computed if fetchmail
              were  connecting  to that server is displayed.  Any non-printable characters in passwords or other
              string names are shown as back-slashed  C-like  escape  sequences.   This  option  is  useful  for
              verifying that your options are set the way you want them.

       -c | --check
              Return  a  status  code  to  indicate  whether there is mail waiting, without actually fetching or
              deleting mail (see EXIT CODES below).  This option turns off daemon mode (in  which  it  would  be
              useless).   It  does  not play well with queries to multiple sites, and does not work with ETRN or
              ODMR.  It will return a false positive if you leave read but undeleted mail in your server mailbox
              and  your  fetch  protocol  cannot tell kept messages from new ones.  This means it will work with
              IMAP, not work with POP2, and may occasionally flake out under POP3.

       -s | --silent
              Silent mode.  Suppresses all progress/status messages that are normally echoed to standard  output
              during  a  fetch  (but  does  not suppress actual error messages).  The --verbose option overrides
              this.

       -v | --verbose
              Verbose mode.  All control messages passed between fetchmail and the mail  server  are  echoed  to
              stdout.   Overrides --silent.  Doubling this option (-v -v) causes extra diagnostic information to
              be printed.

       --nosoftbounce
              (since v6.3.10, Keyword: set no softbounce, since v6.3.10)
              Hard bounce mode. All permanent delivery errors cause messages to be  deleted  from  the  upstream
              server, see "no softbounce" below.

       --softbounce
              (since v6.3.10, Keyword: set softbounce, since v6.3.10)
              Soft  bounce  mode. All permanent delivery errors cause messages to be left on the upstream server
              if the protocol supports that.   This  option  is  on  by  default  to  match  historic  fetchmail
              documentation, and will be changed to hard bounce mode in the next fetchmail release.

   Disposal Options
       -a | --all | (since v6.3.3) --fetchall
              (Keyword: fetchall, since v3.0)
              Retrieve  both  old  (seen)  and  new messages from the mail server.  The default is to fetch only
              messages the server has not marked seen.  Under POP3, this option also  forces  the  use  of  RETR
              rather  than  TOP.   Note  that POP2 retrieval behaves as though --all is always on (see RETRIEVAL
              FAILURE MODES below) and this option does not work with ETRN or ODMR.   While  the  -a  and  --all
              command-line  and  fetchall  rcfile  options  have  been supported for a long time, the --fetchall
              command-line option was added in v6.3.3.

       -k | --keep
              (Keyword: keep)
              Keep retrieved messages on the remote mail server.  Normally, messages are deleted from the folder
              on  the  mail  server after they have been retrieved.  Specifying the keep option causes retrieved
              messages to remain in your folder on the mail server.  This option does  not  work  with  ETRN  or
              ODMR. If used with POP3, it is recommended to also specify the --uidl option or uidl keyword.

       -K | --nokeep
              (Keyword: nokeep)
              Delete  retrieved  messages  from the remote mail server.  This option forces retrieved mail to be
              deleted.  It may be useful if you have specified a default of keep  in  your  .fetchmailrc.   This
              option is forced on with ETRN and ODMR.

       -F | --flush
              (Keyword: flush)
              POP3/IMAP  only.   This  is  a  dangerous  option and can cause mail loss when used improperly. It
              deletes old (seen) messages from the mail server before retrieving new  messages.   Warning:  This
              can  cause mail loss if you check your mail with other clients than fetchmail, and cause fetchmail
              to delete a message it had never fetched before.  It can also cause mail loss if the  mail  server
              marks the message seen after retrieval (IMAP2 servers). You should probably not use this option in
              your configuration file. If you use it with POP3,  you  must  use  the  'uidl'  option.  What  you
              probably  want  is  the  default  setting:  if  you  do  not  specify  '-k',  then  fetchmail will
              automatically delete messages after successful delivery.

       --limitflush
              POP3/IMAP only, since version 6.3.0.  Delete  oversized  messages  from  the  mail  server  before
              retrieving  new  messages.  The size limit should be separately specified with the --limit option.
              This option does not work with ETRN or ODMR.

   Protocol and Query Options
       -p <proto> | --proto <proto> | --protocol <proto>
              (Keyword: proto[col])
              Specify the protocol to use when communicating with the remote mail server.   If  no  protocol  is
              specified, the default is AUTO.  proto may be one of the following:

              AUTO   Tries  IMAP,  POP3, and POP2 (skipping any of these for which support has not been compiled
                     in).

              POP2   Post Office Protocol 2 (legacy, to be removed from future release)

              POP3   Post Office Protocol 3

              APOP   Use POP3 with old-fashioned MD5-challenge authentication.  Considered not resistant to man-
                     in-the-middle attacks.

              RPOP   Use POP3 with RPOP authentication.

              KPOP   Use POP3 with Kerberos V4 authentication on port 1109.

              SDPS   Use POP3 with Demon Internet's SDPS extensions.

              IMAP   IMAP2bis, IMAP4, or IMAP4rev1 (fetchmail automatically detects their capabilities).

              ETRN   Use the ESMTP ETRN option.

              ODMR   Use the On-Demand Mail Relay ESMTP profile.

       All  these  alternatives  work  in  basically the same way (communicating with standard server daemons to
       fetch mail already delivered to a mailbox on the server) except ETRN and ODMR.  The ETRN mode allows  you
       to  ask  a compliant ESMTP server (such as BSD sendmail at release 8.8.0 or higher) to immediately open a
       sender-SMTP connection to your client machine and begin forwarding any items  addressed  to  your  client
       machine  in  the  server's queue of undelivered mail.   The ODMR mode requires an ODMR-capable server and
       works similarly to ETRN, except that it does not require the client machine to have a static DNS.

       -U | --uidl
              (Keyword: uidl)
              Force UIDL use (effective only with POP3).  Force client-side tracking of  'newness'  of  messages
              (UIDL  stands  for  "unique  ID  listing"  and is described in RFC1939).  Use with 'keep' to use a
              mailbox as a baby news drop for a group of users. The fact  that  seen  messages  are  skipped  is
              logged,  unless  error  logging  is  done  through syslog while running in daemon mode.  Note that
              fetchmail may automatically enable this option depending on upstream  server  capabilities.   Note
              also  that  this option may be removed and forced enabled in a future fetchmail version. See also:
              --idfile.

       --idle (since 6.3.3)
              (Keyword: idle, since before 6.0.0)
              Enable IDLE use (effective only with IMAP). Note that this works with only  one  account  and  one
              folder  at  a  given  time,  other  folders or accounts will not be polled when idle is in effect!
              While the idle rcfile keyword had been supported for a long time, the --idle  command-line  option
              was  added in version 6.3.3. IDLE use means that fetchmail tells the IMAP server to send notice of
              new messages, so they can be retrieved sooner than would be possible with regular polls.

       -P <portnumber> | --service <servicename>
              (Keyword: service) Since version 6.3.0.
              The service option permits you to specify a service name to connect to.  You can specify a decimal
              port  number  here, if your services database lacks the required service-port assignments. See the
              FAQ item R12 and the --ssl documentation for details. This replaces the older --port option.

       Note that this does not magically switch between TLS-wrapped and STARTTLS modes, if you  specify  a  port
       number  or  service  name  here  that  is  TLS-wrapped, meaning it starts to negotiate TLS before sending
       application data in the clear, you may need to specify --ssl on the command line or ssl in your rcfile.

       --port <portnumber>
              (Keyword: port)
              Obsolete version of --service that does not take service names.  Note: this option may be  removed
              from a future version.

       --principal <principal>
              (Keyword: principal)
              The  principal  option permits you to specify a service principal for mutual authentication.  This
              is applicable to POP3 or IMAP with Kerberos 4 authentication only.  It does not apply to  Kerberos
              5 or GSSAPI.  This option may be removed in a future fetchmail version.

       -t <seconds> | --timeout <seconds>
              (Keyword: timeout)
              The  timeout  option allows you to set a server-non-response timeout in seconds.  If a mail server
              does not send a greeting message or respond to commands for the given number of seconds, fetchmail
              will  drop  the  connection  to  it.   Without  such  a timeout fetchmail might hang until the TCP
              connection times out, trying to fetch mail from a down host, which may be very long.   This  would
              be  particularly  annoying  for a fetchmail running in the background.  There is a default timeout
              which fetchmail -V will report.  If a given connection receives too many timeouts  in  succession,
              fetchmail  will  consider it wedged and stop retrying.  The calling user will be notified by email
              if this happens.

              Beginning with fetchmail 6.3.10, the SMTP  client  uses  the  recommended  minimum  timeouts  from
              RFC-5321 while waiting for the SMTP/LMTP server it is talking to.  You can raise the timeouts even
              more, but you cannot shorten them. This is to avoid a painful situation where fetchmail  has  been
              configured  with  a  short  timeout  (a minute or less), ships a long message (many MBytes) to the
              local MTA, which then takes longer than timeout to respond "OK", which it  eventually  will;  that
              would mean the mail gets delivered properly, but fetchmail cannot notice it and will thus re-fetch
              this big message over and over again.

       --plugin <command>
              (Keyword: plugin)
              The plugin option allows you to use an external program to establish the TCP connection.  This  is
              useful if you want to use ssh, or need some special firewall setup.  The program will be looked up
              in $PATH and can optionally be passed the host name and port as  arguments  using  "%h"  and  "%p"
              respectively  (note  that  the  interpolation  logic is rather primitive, and these tokens must be
              bounded by whitespace or beginning of string or end of  string).   Fetchmail  will  write  to  the
              plugin's stdin and read from the plugin's stdout.

       --plugout <command>
              (Keyword: plugout)
              Identical to the plugin option above, but this one is used for the SMTP connections.

       -r <name> | --folder <name>
              (Keyword: folder[s])
              Causes a specified non-default mail folder on the mail server (or comma-separated list of folders)
              to be retrieved.  The syntax of the folder name is server-dependent.  This option is not available
              under POP3, ETRN, or ODMR.

       --tracepolls
              (Keyword: tracepolls)
              Tell  fetchmail  to poll trace information in the form 'polling account %s' and 'folder %s' to the
              Received line it generates, where the %s parts are replaced by the user's remote  name,  the  poll
              label,  and  the  folder (mailbox) where available (the Received header also normally includes the
              server's true name).  This can be used to facilitate mail filtering based on  the  account  it  is
              being received from. The folder information is written only since version 6.3.4.

       --ssl  (Keyword: ssl)
              Causes  the  connection  to  the  mail server to be encrypted via SSL, by negotiating SSL directly
              after connecting (called  SSL-wrapped  mode,  or  Implicit  TLS  by  RFC-8314).   Please  see  the
              description  of --sslproto below!  More information is available in the README.SSL file that ships
              with fetchmail.

              Note that even if this option is omitted, fetchmail may still negotiate SSL in-band  for  POP3  or
              IMAP,  through  the  STLS  or  STARTTLS feature.  You can use the --sslproto option to modify that
              behavior.

              If no port is specified, the connection is attempted to the well known port of the SSL version  of
              the  base  protocol.   This is generally a different port than the port used by the base protocol.
              For IMAP, this is port 143 for the clear protocol and port 993 for the SSL secured  protocol;  for
              POP3, it is port 110 for the clear text and port 995 for the encrypted variant.

              If  your  system  lacks the corresponding entries from /etc/services, see the --service option and
              specify the numeric port number as given in the previous paragraph (unless your ISP  had  directed
              you to different ports, which is uncommon however).

       --sslcert <name>
              (Keyword: sslcert)
              For  certificate-based client authentication.  Some SSL encrypted servers require client side keys
              and certificates for authentication.  In  most  cases,  this  is  optional.   This  specifies  the
              location  of  the public key certificate to be presented to the server at the time the SSL session
              is established.  It is not required (but may be provided) if the server does not require  it.   It
              may  be  the  same  file  as  the  private key (combined key and certificate file) but this is not
              recommended. Also see --sslkey below.

              NOTE: If you use client authentication, the user name is fetched from the certificate's CommonName
              and overrides the name set with --user.

       --sslkey <name>
              (Keyword: sslkey)
              Specifies  the  file  name of the client side private SSL key.  Some SSL encrypted servers require
              client side keys and certificates for authentication.  In most  cases,  this  is  optional.   This
              specifies  the  location  of the private key used to sign transactions with the server at the time
              the SSL session is established.  It is not required (but may be provided) if the server  does  not
              require it. It may be the same file as the public key (combined key and certificate file) but this
              is not recommended.

              If a password is required to unlock the key, it will be prompted for at the  time  just  prior  to
              establishing the session to the server.  This can cause some complications in daemon mode.

              Also see --sslcert above.

       --sslproto <value>
              (Keyword: sslproto, NOTE: semantic changes since v6.4.0)
              This  option  has  a  dual  use, out of historic fetchmail behaviour. It controls both the SSL/TLS
              protocol version and, if --ssl is not specified, the STARTTLS behaviour (upgrading the protocol to
              an SSL or TLS connection in-band). Some other options may however make TLS mandatory.

              Only  if  this  option  and --ssl are both missing for a poll, there will be opportunistic TLS for
              POP3 and IMAP, where fetchmail will attempt to upgrade to TLSv1 or newer.

              Recognized values for --sslproto are given below. You should normally  choose  one  of  the  auto-
              negotiating  options,  i.  e. 'tls1.2+' or 'auto' or one of the other options ending in a plus (+)
              character.  Note that depending on OpenSSL library version and configuration, some  options  cause
              run-time  errors  because  the  requested  SSL or TLS versions are not supported by the particular
              installed OpenSSL library.

              'TLS1.2+'
                     (recommended). Since v6.4.0. Require TLS. Auto-negotiate TLSv1.2 or newer.

              'auto' (default). Since  v6.4.0.  Require  TLS.  Auto-negotiate  TLSv1  or  newer,  disable  SSLv3
                     downgrade.   (fetchmail  6.3.26  and  older  have  auto-negotiated all protocols that their
                     OpenSSL library supported, including the broken SSLv3).

              '', the empty string
                     Disable STARTTLS. If --ssl is given for the same server, log  an  error  and  pretend  that
                     'auto' had been used instead.

              'SSL23'
                     see 'auto'.

              'SSL3' Require SSLv3 exactly. SSLv3 is broken, not supported on all systems, avoid it if possible.
                     This will make fetchmail negotiate SSLv3 only, and is the only way besides 'SSL3+' to  have
                     fetchmail 6.4.0 or newer permit SSLv3.

              'SSL3+'
                     same  as  'auto',  but  permit  SSLv3  as well. This is the only way besides 'SSL3' to have
                     fetchmail 6.4.0 or newer permit SSLv3.

              'TLS1' Require TLSv1. This does not negotiate TLSv1.1 or newer, and  is  discouraged.  Replace  by
                     TLS1+ unless the latter chokes your server.

              'TLS1+'
                     Since v6.4.0. See 'auto'.

              'TLS1.1'
                     Since v6.4.0. Require TLS v1.1 exactly.

              'TLS1.1+'
                     Since v6.4.0. Require TLS. Auto-negotiate TLSv1.1 or newer.

              'TLS1.2'
                     Since v6.4.0. Require TLS v1.2 exactly.

              'TLS1.3'
                     Since v6.4.0. Require TLS v1.3 exactly.

              'TLS1.3+'
                     Since v6.4.0. Require TLS. Auto-negotiate TLSv1.3 or newer.

              Unrecognized parameters
                     are treated the same as 'auto'.

              NOTE:  you  should  hardly  ever  need  to  use  anything  other  than '' (to force an unencrypted
              connection) or 'auto' (to enforce TLS).

       --sslcertck
              (Keyword: sslcertck, default enabled since v6.4.0)
              --sslcertck causes fetchmail to require  that  SSL/TLS  be  used  and  disconnect  unless  it  can
              successfully  negotiate  SSL  or  TLS,  or  if  it  cannot  successfully  verify  and validate the
              certificate and follow it to a trust anchor (or trusted root certificate). The trust  anchors  are
              given as a set of local trusted certificates (see the sslcertfile and sslcertpath options). If the
              server certificate cannot be obtained or is not signed by one of the  trusted  ones  (directly  or
              indirectly), fetchmail will disconnect, regardless of the sslfingerprint option.

       --nosslcertck
              (Keyword: no sslcertck, only in v6.4.X)
              The  opposite  of  --sslcertck,  this  is  a  discouraged option. It permits fetchmail to continue
              connecting even if the server certificate failed the verification checks.   Should  only  be  used
              together with --sslfingerprint.

       --sslcertfile <file>
              (Keyword: sslcertfile, since v6.3.17)
              Sets  the  file  fetchmail uses to look up local certificates.  The default is empty.  This can be
              given in addition to --sslcertpath below, and certificates  specified  in  --sslcertfile  will  be
              processed before those in --sslcertpath.  The option can be used in addition to --sslcertpath.

              The file is a text file. It contains the concatenation of trusted CA certificates in PEM format.

              Note  that  using  this  option will suppress loading the default SSL trusted CA certificates file
              unless you set the environment variable  FETCHMAIL_INCLUDE_DEFAULT_X509_CA_CERTS  to  a  non-empty
              value.

       --sslcertpath <directory>
              (Keyword: sslcertpath)
              Sets  the  directory  fetchmail  uses  to  look up local certificates. The default is your OpenSSL
              default directory. The directory must be hashed the way OpenSSL expects it - every time you add or
              modify a certificate in the directory, you need to use the c_rehash tool (which comes with OpenSSL
              in the tools/ sub-directory). Also, after OpenSSL upgrades, you may need to run c_rehash.

              This can be given in addition to --sslcertfile above, which see for precedence rules.

              Note that using this option will suppress adding the default SSL trusted CA certificates directory
              unless  you  set  the  environment variable FETCHMAIL_INCLUDE_DEFAULT_X509_CA_CERTS to a non-empty
              value.

       --sslcommonname <common name>
              (Keyword: sslcommonname; since v6.3.9)
              Use of this option is discouraged. Before using it, contact the  administrator  of  your  upstream
              server  and  ask  for a proper SSL certificate to be used. If that cannot be attained, this option
              can be used to specify the name (CommonName) that fetchmail expects on the server certificate.   A
              correctly  configured  server  will  have this set to the host name by which it is reached, and by
              default fetchmail will expect as much. Use this option when the CommonName is set  to  some  other
              value,  to  avoid  the  "Server  CommonName  mismatch"  warning, and only if the upstream server's
              operator cannot be made to use proper certificates.

       --sslfingerprint <fingerprint>
              (Keyword: sslfingerprint)
              Specify the fingerprint of the server key (an MD5 hash of the key) in  hexadecimal  notation  with
              colons  separating  groups of two digits. The letter hex digits must be in upper case. This is the
              format that fetchmail uses to report the fingerprint when an SSL connection is  established.  When
              this  is  specified, fetchmail will compare the server key fingerprint with the given one, and the
              connection will fail if they do not match, regardless of the  sslcertck  setting.  The  connection
              will also fail if fetchmail cannot obtain an SSL certificate from the server.  This can be used to
              prevent man-in-the-middle attacks, but the finger print  from  the  server  must  be  obtained  or
              verified over a secure channel, and certainly not over the same Internet connection that fetchmail
              would use.

              Using this option will prevent printing certificate verification errors as long  as  --nosslcertck
              is in effect.

              To obtain the fingerprint of a certificate stored in the file cert.pem, try:

                   openssl x509 -in cert.pem -noout -md5 -fingerprint

              For details, see x509(1ssl).

   Delivery Control Options
       -S <hosts> | --smtphost <hosts>
              (Keyword: smtp[host])
              Specify  a  hunt list of hosts to forward mail to (one or more host names, comma-separated). Hosts
              are tried in list order; the first one that is up becomes the forwarding target  for  the  current
              run.   If  this  option  is not specified, 'localhost' is used as the default.  Each host name may
              have a port number following the host name.  The port number is separated from the host name by  a
              slash;  the default port is "smtp".  If you specify an absolute path name (beginning with a /), it
              will be interpreted as the name of a UNIX socket accepting LMTP connections (such as is  supported
              by the Cyrus IMAP daemon) Example:

                   --smtphost server1,server2/2525,server3,/var/imap/socket/lmtp

              This  option  can  be  used with ODMR, and will make fetchmail a relay between the ODMR server and
              SMTP or LMTP receiver.

              WARNING: if you use address numeric IP addresses here, be sure to use --smtpaddress or  --smtpname
              (either of which see) with a valid SMTP address literal!

       --fetchdomains <hosts>
              (Keyword: fetchdomains)
              In  ETRN  or  ODMR mode, this option specifies the list of domains the server should ship mail for
              once the connection is turned around.  The default is the FQDN of the machine running fetchmail.

       -D <domain> | --smtpaddress <domain>
              (Keyword: smtpaddress)
              Specify the domain to be appended to addresses in RCPT TO lines shipped to SMTP. When this is  not
              specified,  the  name  of  the  SMTP server (as specified by --smtphost) is used for SMTP/LMTP and
              'localhost' is used for UNIX socket/BSMTP.

              NOTE: if you intend to use numeric addresses, or so-called address literals per the SMTP standard,
              write  them  in  proper  SMTP  syntax,  for  instance --smtpaddress "[192.0.2.6]" or --smtpaddress
              "[IPv6:2001:DB8::6]".

       --smtpname <user@domain>
              (Keyword: smtpname)
              Specify the domain and user to be put in RCPT TO lines shipped to SMTP.  The default user  is  the
              current local user. Please also see the NOTE about --smtpaddress and address literals above.

       -Z <nnn> | --antispam <nnn[, nnn]...>
              (Keyword: antispam)
              Specifies the list of numeric SMTP errors that are to be interpreted as a spam-block response from
              the listener.  A value of -1 disables this option.  For the command-line option, the  list  values
              should  be  comma-separated.  Note that the antispam values only apply to "MAIL FROM" responses in
              the SMTP/LMTP dialogue, but several MTAs (Postfix in its default configuration, qmail)  defer  the
              anti-spam  response code until after the RCPT TO. --antispam does not work in these circumstances.
              Also see --softbounce (default) and its inverse.

       -m <command> | --mda <command>
              (Keyword: mda)
              This option lets fetchmail use a Message or Local Delivery Agent (MDA  or  LDA)  directly,  rather
              than forward via SMTP or LMTP.

              To avoid losing mail, use this option only with MDAs like maildrop or MTAs like sendmail that exit
              with a nonzero status on disk-full and other delivery errors; the nonzero status  tells  fetchmail
              that delivery failed and prevents the message from being deleted on the server.

              If  fetchmail  is  running  as  root,  it sets its user id while delivering mail through an MDA as
              follows:  First, the FETCHMAILUSER, LOGNAME, and USER environment variables are  checked  in  this
              order.  The  value  of  the first variable from his list that is defined (even if it is empty!) is
              looked up in the system user database. If none of the variables is defined, fetchmail will use the
              real  user  id it was started with. If one of the variables was defined, but the user stated there
              is not found, fetchmail continues running as root, without checking  remaining  variables  on  the
              list.   Practically,  this  means  that if you run fetchmail as root (not recommended), it is most
              useful to define the FETCHMAILUSER environment variable to set the user that the  MDA  should  run
              as. Some MDAs (such as maildrop) are designed to be setuid root and setuid to the recipient's user
              id, so you do not lose functionality this way even when running fetchmail  as  unprivileged  user.
              Check the MDA's manual for details.

              Some  possible  MDAs  are  "/usr/sbin/sendmail -i -f %F -- %T" (Note: some several older or vendor
              sendmail versions mistake -- for an address, rather than an indicator  to  mark  the  end  of  the
              option  arguments),  "/usr/bin/deliver"  and  "/usr/bin/maildrop -d %T".  Local delivery addresses
              will be inserted into the MDA command wherever you place a %T; the  mail  message's  From  address
              will be inserted where you place an %F.

              Do  NOT  enclose the %F or %T string in single quotes!  For both %T and %F, fetchmail encloses the
              addresses in single quotes ('), after removing any single quotes they may contain, before the  MDA
              command is passed to the shell.

              Do  NOT  use an MDA invocation that dispatches on the contents of To/Cc/Bcc, like "sendmail -i -t"
              or "qmail-inject", it will create mail loops and bring the just wrath  of  many  postmasters  down
              upon your head.  This is one of the most frequent configuration errors!

              Also,  do  not try to combine multidrop mode with an MDA such as maildrop that can only accept one
              address, unless your upstream stores one copy of the message  per  recipient  and  transports  the
              envelope recipient in a header; you will lose mail.

              The  well-known  procmail(1) package is very hard to configure properly, it has a very nasty "fall
              through to the next rule" behavior on delivery errors (even temporary ones, such as  out  of  disk
              space if another user's mail daemon copies the mailbox around to purge old messages), so your mail
              will end up in the wrong mailbox sooner or later. The proper procmail configuration is outside the
              scope  of  this document. Using maildrop(1) is usually much easier, and many users find the filter
              syntax used by maildrop easier to understand.

              Finally, we strongly advise that you do not use qmail-inject.  The command line interface is  non-
              standard  without  providing  benefits  for  typical  use,  and  fetchmail  makes  no  attempts to
              accommodate qmail-inject's deviations from the standard. Some of qmail-inject's  command-line  and
              environment  options  are  actually dangerous and can cause broken threads, non-detected duplicate
              messages and forwarding loops.

       --lmtp (Keyword: lmtp)
              Cause delivery via LMTP (Local  Mail  Transfer  Protocol).   A  service  host  and  port  must  be
              explicitly  specified  on  each  host  in  the  smtphost  hunt  list (see above) if this option is
              selected; the default port 25 will (in accordance with RFC 2033) not be accepted.

       --bsmtp <filename>
              (Keyword: bsmtp)
              Append fetched mail to a BSMTP file.  This simply contains the SMTP commands that  would  normally
              be generated by fetchmail when passing mail to an SMTP listener daemon.

              An  argument  of  '-'  causes the SMTP batch to be written to standard output, which is of limited
              use: this only makes sense for debugging, because fetchmail's regular output  is  interspersed  on
              the same channel, so this is not suitable for mail delivery. This special mode may be removed in a
              later release.

              Note that fetchmail's reconstruction of MAIL FROM and RCPT TO lines is not guaranteed correct; the
              caveats  discussed  under  THE  USE  AND  ABUSE OF MULTIDROP MAILBOXES below apply.  This mode has
              precedence before --mda and SMTP/LMTP.

       --bad-header {reject|accept}
              (Keyword: bad-header; since v6.3.15)
              Specify how fetchmail is supposed to treat messages with  bad  headers,  i.e.,  headers  with  bad
              syntax.  Traditionally,  fetchmail  has  rejected  such  messages,  but some distributors modified
              fetchmail to accept them. You can now configure fetchmail's behaviour per server.

   Resource Limit Control Options
       -l <maxbytes> | --limit <maxbytes>
              (Keyword: limit)
              Takes a maximum octet size argument, where 0 is the default and also the special value designating
              "no  limit".   If  nonzero, messages larger than this size will not be fetched and will be left on
              the server (in foreground sessions, the progress messages will note that  they  are  "oversized").
              If  the fetch protocol permits (in particular, under IMAP or POP3 without the fetchall option) the
              message will not be marked seen.

              An explicit --limit of 0 overrides any limits set  in  your  run  control  file.  This  option  is
              intended  for  those  needing  to  strictly control fetch time due to expensive and variable phone
              rates.

              Combined with --limitflush, it can be used to delete oversized messages waiting on a  server.   In
              daemon  mode,  oversize  notifications are mailed to the calling user (see the --warnings option).
              This option does not work with ETRN or ODMR.

       -w <interval> | --warnings <interval>
              (Keyword: warnings)
              Takes an interval in seconds.  When you call fetchmail with a 'limit' option in daemon mode,  this
              controls  the  interval  at which warnings about oversized messages are mailed to the calling user
              (or the user specified by the 'postmaster' option).  One such notification is always mailed at the
              end  of  the  first  poll  that the oversized message is detected.  Thereafter, re-notification is
              suppressed until after the warning interval elapses (it will take place at the end  of  the  first
              following poll).

       -b <count> | --batchlimit <count>
              (Keyword: batchlimit)
              Specify  the  maximum  number  of  messages  that  will  be shipped to an SMTP listener before the
              connection is deliberately torn down and rebuilt (defaults to 0, meaning no limit).   An  explicit
              --batchlimit  of  0 overrides any limits set in your run control file.  While sendmail(8) normally
              initiates delivery of a message immediately after receiving  the  message  terminator,  some  SMTP
              listeners are not so prompt.  MTAs like smail(8) may wait till the delivery socket is shut down to
              deliver.  This may produce annoying delays  when  fetchmail  is  processing  very  large  batches.
              Setting the batch limit to some nonzero size will prevent these delays.  This option does not work
              with ETRN or ODMR.

       -B <number> | --fetchlimit <number>
              (Keyword: fetchlimit)
              Limit the number of messages accepted from a given server in a single poll.  By default  there  is
              no  limit.  An explicit --fetchlimit of 0 overrides any limits set in your run control file.  This
              option does not work with ETRN or ODMR.

       --fetchsizelimit <number>
              (Keyword: fetchsizelimit)
              Limit the number of sizes of messages accepted from a given server in a single transaction.   This
              option is useful in reducing the delay in downloading the first mail when there are too many mails
              in the mailbox.  By default, the limit is 100.  If set to 0, sizes of all messages are  downloaded
              at  the  start.   This  option does not work with ETRN or ODMR.  For POP3, the only valid non-zero
              value is 1.

       --fastuidl <number>
              (Keyword: fastuidl)
              Do a binary instead of linear search for the first unseen UID. Binary  search  avoids  downloading
              the  UIDs of all mails. This saves time (especially in daemon mode) where downloading the same set
              of UIDs in each poll is a waste of bandwidth. The number 'n' indicates how rarely a linear  search
              should  be  done.  In daemon mode, linear search is used once followed by binary searches in 'n-1'
              polls if 'n' is greater than 1; binary search is always used if 'n' is 1; linear search is  always
              used  if  'n' is 0. In non-daemon mode, binary search is used if 'n' is 1; otherwise linear search
              is used. The default value of 'n' is 4.  This option works with POP3 only.

       -e <count> | --expunge <count>
              (Keyword: expunge)
              Arrange for deletions to be made final after a given number of  messages.   Under  POP2  or  POP3,
              fetchmail  cannot  make  deletions  final without sending QUIT and ending the session -- with this
              option on, fetchmail will break a long mail retrieval session into multiple sub-sessions,  sending
              QUIT  after  each  sub-session.  This is a good defense against line drops on POP3 servers.  Under
              IMAP, fetchmail normally issues an EXPUNGE command after each  deletion  in  order  to  force  the
              deletion  to  be done immediately.  This is safest when your connection to the server is flaky and
              expensive, as it avoids re-sending duplicate mail after a line hit.  However, on  large  mailboxes
              the  overhead  of  re-indexing  after  every  message  can slam the server pretty hard, so if your
              connection is reliable it is good to do expunges less frequently.  Also  note  that  some  servers
              enforce  a  delay  of  a  few seconds after each quit, so fetchmail may not be able to get back in
              immediately after an expunge -- you may see "lock busy" errors if this  happens.  If  you  specify
              this  option  to  an integer N, it tells fetchmail to only issue expunges on every Nth delete.  An
              argument of zero suppresses expunges entirely (so no expunges at all will be done until the end of
              run).  This option does not work with ETRN or ODMR.

   Authentication Options
       -u <name> | --user <name> | --username <name>
              (Keyword: user[name])
              Specifies  the user identification to be used when logging in to the mail server.  The appropriate
              user identification is both server and user-dependent.  The default is  your  login  name  on  the
              client  machine  that  is  running  fetchmail.   See  USER  AUTHENTICATION  below  for  a complete
              description.

       -I <specification> | --interface <specification>
              (Keyword: interface)
              Require that a specific interface device be up and have a specific local or remote IPv4  (IPv6  is
              not supported by this option yet) address (or range) before polling.  Frequently fetchmail is used
              over a transient point-to-point TCP/IP link established directly to a mail server via SLIP or PPP.
              That is a relatively secure channel.  But when other TCP/IP routes to the mail server exist (e.g.,
              when the link is connected to an alternate ISP), your username and password may be  vulnerable  to
              snooping (especially when daemon mode automatically polls for mail, shipping a clear password over
              the net at predictable intervals).  The --interface option may be used to prevent this.  When  the
              specified  link  is  not up or is not connected to a matching IP address, polling will be skipped.
              The format is:

                   interface/iii.iii.iii.iii[/mmm.mmm.mmm.mmm]

              The field before the first slash is the interface name (i.e., sl0, ppp0 etc.).  The  field  before
              the  second  slash is the acceptable IP address.  The field after the second slash is a mask which
              specifies a range of IP addresses to accept.  If no mask is  present  255.255.255.255  is  assumed
              (i.e.,  an  exact match).  This option is currently only supported under Linux and FreeBSD. Please
              see the monitor section for below for FreeBSD specific information.

              Note that this option may be removed from a future fetchmail version.

       -M <interface> | --monitor <interface>
              (Keyword: monitor)
              Daemon mode can cause transient links which  are  automatically  taken  down  after  a  period  of
              inactivity  (e.g.,  PPP  links) to remain up indefinitely.  This option identifies a system TCP/IP
              interface to be monitored for activity.  After each poll interval, if the link is up but no  other
              activity  has  occurred  on  the  link, then the poll will be skipped.  However, when fetchmail is
              woken up by a signal, the monitor check is skipped and  the  poll  goes  through  unconditionally.
              This  option  is  currently only supported under Linux and FreeBSD.  For the monitor and interface
              options to work for non root users under FreeBSD, the fetchmail binary must  be  installed  setgid
              kmem.  This would be a security hole, but fetchmail runs with the effective GID set to that of the
              kmem group only when interface data is being collected.

              Note that this option may be removed from a future fetchmail version.

       --auth <type>
              (Keyword: auth[enticate])
              This option permits you to specify an authentication  type  (see  USER  AUTHENTICATION  below  for
              details).   The  possible  values  are  any, password, kerberos_v5, kerberos (or, for excruciating
              exactness, kerberos_v4), gssapi, cram-md5, otp, ntlm, msn (only for POP3),  external  (only  IMAP)
              and ssh.  When any (the default) is specified, fetchmail tries first methods that do not require a
              password (EXTERNAL, GSSAPI, KERBEROS IV, KERBEROS 5); then it looks for  methods  that  mask  your
              password  (CRAM-MD5, NTLM, X-OTP - note that MSN is only supported for POP3, but not auto-probed);
              and only if the server does not support any of those  will  it  ship  your  password  unencrypted.
              Other  values  may  be used to force various authentication methods: ssh suppresses authentication
              and is thus useful for IMAP PREAUTH (if you are using a secure --plugin, for instance, a  properly
              configured ssh, you may also need to set --sslproto '' or, in the rcfile, sslproto '', in order to
              avoid fetchmail negotiating STARTTLS over SSH).  external suppresses authentication  and  is  thus
              useful  for  IMAP  EXTERNAL.  Any value other than password, cram-md5, ntlm, msn or otp suppresses
              fetchmail's normal inquiry for a password.  Specify ssh when you are using  an  end-to-end  secure
              connection  such  as an ssh tunnel (in this case you may also want to specify --sslproto '', which
              see); specify external when  you  use  TLS  with  client  authentication  and  specify  gssapi  or
              kerberos_v4 if you are using a protocol variant that employs GSSAPI or K4.  Choosing KPOP protocol
              automatically selects Kerberos authentication.  This option  does  not  work  with  ETRN.   GSSAPI
              service  names  are  in  line  with  RFC-2743 and IANA registrations, see Generic Security Service
              Application Program Interface (GSSAPI)/Kerberos/Simple Authentication and  Security  Layer  (SASL)
              Service Names ⟨https://www.iana.org/assignments/gssapi-service-names/⟩.

   Miscellaneous Options
       -f <pathname> | --fetchmailrc <pathname>
              Specify a non-default name for the ~/.fetchmailrc run control file.  The pathname argument must be
              either "-" (a single dash, meaning to read the configuration from standard input) or  a  filename.
              Unless  the  --version option is also on, a named file argument must have permissions no more open
              than 0700 (u=rwx,g=,o=) or else be /dev/null.

       -i <pathname> | --idfile <pathname>
              (Keyword: idfile)
              Specify an alternate name for the .fetchids file used to save message UIDs. NOTE: since  fetchmail
              6.3.0,  write  access  to  the  directory containing the idfile is required, as fetchmail writes a
              temporary file and renames it into the place of the real idfile only if  the  temporary  file  has
              been written successfully. This avoids the truncation of idfiles when running out of disk space.

       --pidfile <pathname>
              (Keyword: pidfile; since fetchmail v6.3.4)
              Override  the  default  location  of  the  PID  file  that  is  used as a lock file.  Default: see
              "ENVIRONMENT" below. Note that many places in the code and documentation, the term "lock file"  is
              used.   This  file  contains  the  process  ID  of  the  running  fetchmail  on the first line and
              potentially the daemon interval on a second line.

       -n | --norewrite
              (Keyword: no rewrite)
              Normally, fetchmail edits RFC-822 address headers (To, From, Cc, Bcc,  and  Reply-To)  in  fetched
              mail  so  that  any  mail  IDs  local to the server are expanded to full addresses (@ and the mail
              server host name are appended).  This enables replies on the client  to  get  addressed  correctly
              (otherwise  your  mailer  might  think  they  should  be  addressed  to  local users on the client
              machine!).  This option disables the rewrite.  (This option is provided to pacify people  who  are
              paranoid  about  having  an  MTA edit mail headers and want to know they can prevent it, but it is
              generally not a good idea to actually turn off rewrite.)  When using ETRN  or  ODMR,  the  rewrite
              option is ineffective.

       -E <line> | --envelope <line>
              (Keyword: envelope; Multidrop only)
              In the configuration file, an enhanced syntax is used:
              envelope [<count>] <line>

              This option changes the header fetchmail assumes will carry a copy of the mail's envelope address.
              Normally this is 'X-Envelope-To'.  Other typically found headers to carry envelope information are
              'X-Original-To'  and  'Delivered-To'.   Now,  since  these  headers are not standardized, practice
              varies. See the discussion of multidrop address handling below.   As  a  special  case,  'envelope
              "Received"'  enables  parsing  of  sendmail-style  Received  lines.   This  is  the  default,  but
              discouraged because it is not fully reliable.

              Note that fetchmail expects the Received-line to be in a specific format: It must contain "by host
              for address", where host must match one of the mail server names that fetchmail recognizes for the
              account in question.

              The optional count argument (only available in the configuration file) determines how many  header
              lines  of this kind are skipped. A count of 1 means: skip the first, take the second. A count of 2
              means: skip the first and second, take the third, and so on.

       -Q <prefix> | --qvirtual <prefix>
              (Keyword: qvirtual; Multidrop only)
              The string prefix assigned to this option will be removed from the user name found in  the  header
              specified  with  the envelope option (before doing multidrop name mapping or localdomain checking,
              if either is applicable). This option is useful if you are using fetchmail to collect the mail for
              an  entire  domain  and  your  ISP (or your mail redirection provider) is using qmail.  One of the
              basic features of qmail is the Delivered-To: message header.  Whenever qmail delivers a message to
              a  local  mailbox  it puts the username and host name of the envelope recipient on this line.  The
              major reason for this is to prevent mail loops.  To set up qmail to batch mail for a  disconnected
              site  the  ISP-mailhost  will have normally put that site in its 'Virtualhosts' control file so it
              will add  a  prefix  to  all  mail  addresses  for  this  site.  This  results  in  mail  sent  to
              'username@userhost.userdom.dom.com' having a Delivered-To: line of the form:

              Delivered-To: mbox-userstr-username@userhost.example.com

              The  ISP  can  make the 'mbox-userstr-' prefix anything they choose but a string matching the user
              host name is likely.  By using the option 'envelope Delivered-To:' you can make fetchmail reliably
              identify  the  original  envelope  recipient,  but you have to strip the 'mbox-userstr-' prefix to
              deliver to the correct user.  This is what this option is for.

       --configdump
              Parse  the  ~/.fetchmailrc  file,  interpret  any  command-line  options  specified,  and  dump  a
              configuration  report to standard output.  The configuration report is a data structure assignment
              in the language Python.  This option is meant to be used with an interactive ~/.fetchmailrc editor
              like fetchmailconf, written in Python.

       -y | --yydebug
              Enables parser debugging, this option is meant to be used by developers only.

   Removed Options
       -T | --netsec
              Removed before version 6.3.0, the required underlying inet6_apps library had been discontinued and
              is no longer available.

USER AUTHENTICATION AND ENCRYPTION

       All modes except ETRN require authentication of the client to the server.  Normal user authentication  in
       fetchmail  is  very  much  like the authentication mechanism of ftp(1).  The correct user-id and password
       depend upon the underlying security system at the mail server.

       If the mail server is a Unix machine on which you have an ordinary user account, your regular login  name
       and  password  are used with fetchmail.  If you use the same login name on both the server and the client
       machines, you needn't worry about specifying a user-id with the -u option -- the default behavior  is  to
       use  your  login name on the client machine as the user-id on the server machine.  If you use a different
       login name on the server machine, specify that login name with the -u option.  E.g., if your  login  name
       is 'jsmith' on a machine named 'mailgrunt', you would start fetchmail as follows:

              fetchmail -u jsmith mailgrunt

       The default behavior of fetchmail is to prompt you for your mail server password before the connection is
       established.  This is the safest way to use  fetchmail  and  ensures  that  your  password  will  not  be
       compromised.   You  may  also specify your password in your ~/.fetchmailrc file.  This is convenient when
       using fetchmail in daemon mode or with scripts.

   Using netrc files
       If you do not specify a password, and fetchmail cannot extract one from your ~/.fetchmailrc file, it will
       look for a ~/.netrc file in your home directory before requesting one interactively; if an entry matching
       the mail server is found in that file, the password will be used.  Fetchmail first looks for a  match  on
       poll  name;  if it finds none, it checks for a match on via name.  See the ftp(1) man page for details of
       the syntax of the ~/.netrc file.  To show a practical example, a .netrc might look like this:

              machine hermes.example.org
              login joe
              password topsecret

       You can repeat this block with different user information if you need to provide more than one password.

       This feature may allow you to avoid duplicating password information in more than one file.

       On mail servers that do not provide ordinary  user  accounts,  your  user-id  and  password  are  usually
       assigned  by  the  server  administrator when you apply for a mailbox on the server.  Contact your server
       administrator if you do not know the correct user-id and password for your mailbox account.

   Secure Socket Layers (SSL) and Transport Layer Security (TLS)
       All retrieval protocols can use SSL or TLS wrapping  for  the  transport.  Additionally,  POP3  and  IMAP
       retrieval can also negotiate SSL/TLS by means of STARTTLS (or STLS).

       You  can  access  TLS-encrypted  services  by  specifying the options starting with --ssl, such as --ssl,
       --sslproto, --sslcertck, and others.  You can also do this using the corresponding user  options  in  the
       .fetchmailrc file.  Some services, such as POP3 and IMAP, have different well known ports defined for the
       SSL encrypted services.  The encrypted ports will be selected automatically when SSL is  enabled  and  no
       explicit  port  is  specified.    Also, the --sslcertck command line or sslcertck run control file option
       should be used to force strict certificate checking with older fetchmail versions - see below.

       If  TLS  or  SSL  is  not  configured,  fetchmail  will  usually  still  try  to  use  STARTTLS  somewhat
       opportunistically.  In  practice,  is  it  still  mandatory  because --sslcertck is a default setting and
       implicitly requires STARTTLS.

       STARTTLS can be enforced by using  --sslproto  auto  and  defeated  by  using  --sslproto  ''.   STARTTLS
       connections  use  the  same port as the unencrypted version of the protocol and negotiate TLS via special
       command. The --sslcertck command line or sslcertck run control file option should be used to force strict
       certificate checking - see below.

       --sslcertck  is  recommended:  When  connecting  to an SSL or TLS encrypted server, the server presents a
       certificate to the client for validation.  The certificate is checked to verify that the common  name  in
       the  certificate  matches  the  name  of the server being contacted and that the effective and expiration
       dates in the certificate indicate that it is currently valid.  If any of these  checks  fail,  a  warning
       message  is  printed, but the connection continues.  The server certificate does not need to be signed by
       any specific Certifying Authority and may be a "self-signed" certificate. If the --sslcertck command line
       option  or sslcertck run control file option is used, fetchmail will instead abort if any of these checks
       fail, because it must assume that there is a man-in-the-middle attack in this scenario,  hence  fetchmail
       must not expose clear-text passwords. Use of the sslcertck or --sslcertck option is therefore advised; it
       has become the default in fetchmail 6.4.0.

       Some SSL encrypted servers may request a client side certificate.  A client side public  SSL  certificate
       and  private SSL key may be specified.  If requested by the server, the client certificate is sent to the
       server for validation.  Some servers may require a valid client certificate and may refuse connections if
       a  certificate  is not provided or if the certificate is not valid.  Some servers may require client side
       certificates be signed by a recognized Certifying Authority.  The  format  for  the  key  files  and  the
       certificate files is that required by the underlying SSL libraries (OpenSSL in the general case).

       A  word  of  care  about the use of SSL: While above mentioned setup with self-signed server certificates
       retrieved over the wires can protect you from a passive eavesdropper, it does not help against an  active
       attacker.  It is clearly an improvement over sending the passwords in clear, but you should be aware that
       a  man-in-the-middle  attack  is  trivially  possible  (in  particular  with   tools   such   as   dsniff
       ⟨https://monkey.org/~dugsong/dsniff/⟩).    Use  of  strict  certificate  checking  with  a  certification
       authority recognized by server and client, or perhaps of an SSH tunnel (see below for some  examples)  is
       preferable if you care seriously about the security of your mailbox and passwords.

POP3 VARIANTS

       Early  versions of POP3 (RFC1081, RFC1225) supported a crude form of independent authentication using the
       .rhosts file on the mail server side.  Under this RPOP variant, a  fixed  per-user  ID  equivalent  to  a
       password  was  sent  in  clear  over a link to a reserved port, with the command RPOP rather than PASS to
       alert the server that it should do special checking.  RPOP is supported by  fetchmail  (you  can  specify
       'protocol  RPOP' to have the program send 'RPOP' rather than 'PASS') but its use is strongly discouraged,
       and support will be removed from a future fetchmail version.  This facility was  vulnerable  to  spoofing
       and was withdrawn in RFC1460.

       RFC1460  introduced  APOP authentication.  In this variant of POP3, you register an APOP password on your
       server host (on some servers, the program to do this is called popauth(8)).  You put the same password in
       your  ~/.fetchmailrc  file.   Each  time fetchmail logs in, it sends an MD5 hash of your password and the
       server greeting time to the server, which can verify it by checking its authorization database.

       Note that APOP is no longer considered resistant against man-in-the-middle attacks.

   RETR or TOP
       fetchmail makes some efforts to make the server believe messages had not been retrieved, by using the TOP
       command  with a large number of lines when possible.  TOP is a command that retrieves the full header and
       a fetchmail-specified amount of body lines. It is optional and therefore not implemented by all  servers,
       and  some are known to implement it improperly. On many servers however, the RETR command which retrieves
       the full message with header and body, sets the "seen" flag (for instance, in a web  interface),  whereas
       the TOP command does not do that.

       fetchmail  will  always  use  the  RETR  command  if "fetchall" is set.  fetchmail will also use the RETR
       command if "keep" is set and  "uidl"  is  unset.   Finally,  fetchmail  will  use  the  RETR  command  on
       Maillennium  POP3/PROXY  servers  (used  by  Comcast) to avoid a deliberate TOP misinterpretation in this
       server that causes message corruption.

       In all other cases, fetchmail will use the TOP command. This implies that in "keep" setups,  "uidl"  must
       be set if "TOP" is desired.

       Note  that  this description is true for the current version of fetchmail, but the behavior may change in
       future versions. In particular, fetchmail may prefer the RETR command because the TOP command causes much
       grief on some servers and is only optional.

ALTERNATE AUTHENTICATION FORMS/METHODS

       If  your  fetchmail  was built with Kerberos support and you specify Kerberos authentication (either with
       --auth or the .fetchmailrc option authenticate kerberos_v4) it will try to get a Kerberos ticket from the
       mail  server at the start of each query.  Note: if either the pollname or via name is 'hesiod', fetchmail
       will try to use Hesiod to look up the mail server.

       If you use POP3 or IMAP with GSSAPI authentication, fetchmail will expect the server to have RFC1731-  or
       RFC1734-conforming  GSSAPI  capability,  and  will  use  it.   Currently  this  has only been tested over
       Kerberos 5, so you are expected to already have  a  ticket-granting  ticket.  You  may  pass  a  username
       different from your principal name using the standard --user command or by the .fetchmailrc option user.

       If  your  IMAP  daemon  returns the PREAUTH response in its greeting line, fetchmail will notice this and
       skip the normal authentication step.  This can be useful, e.g., if you start imapd explicitly using  ssh.
       In  this  case  you can declare the authentication value 'ssh' on that site entry to stop .fetchmail from
       asking you for a password when it starts up.

       If you use client authentication with TLS1 and your  IMAP  daemon  returns  the  AUTH=EXTERNAL  response,
       fetchmail  will notice this and will use the authentication shortcut and will not send the passphrase. In
       this case you can declare the authentication value 'external'
        on that site to stop fetchmail from asking you for a password when it starts up.

       If you are using POP3, and the  server  issues  a  one-time-password  challenge  conforming  to  RFC1938,
       fetchmail  will use your password as a pass phrase to generate the required response. This avoids sending
       secrets over the net unencrypted.

       Compuserve's RPA authentication is supported. If you compile  in  the  support,  fetchmail  will  try  to
       perform  an RPA pass-phrase authentication instead of sending over the password unencrypted if it detects
       "@compuserve.com" in the host name.

       If you are using IMAP, Microsoft's NTLM authentication (used by Microsoft Exchange) is supported. If  you
       compile in the support, fetchmail will try to perform an NTLM authentication (instead of sending over the
       password unencrypted) whenever the server returns AUTH=NTLM in its capability response.  Specify  a  user
       option  value that looks like 'user@domain': the part to the left of the @ will be passed as the username
       and the part to the right as the NTLM domain.

   ESMTP AUTH
       fetchmail also supports authentication to the ESMTP server on the client side according to RFC 2554.  You
       can specify a name/password pair to be used with the keywords 'esmtpname' and 'esmtppassword'; the former
       defaults to the username of the calling user.

DAEMON MODE

   Introducing the daemon mode
       In daemon mode, fetchmail puts itself into the background and runs forever, querying each specified  host
       and then sleeping for a given polling interval.

   Starting the daemon mode
       There are several ways to make fetchmail work in daemon mode. On the command line, --daemon <interval> or
       -d <interval> option runs fetchmail in daemon mode.  You must specify  a  numeric  argument  which  is  a
       polling  interval  (time  to  wait  after  completing  a whole poll cycle with the last server and before
       starting the next poll cycle with the first server) in seconds.

       Example: simply invoking

              fetchmail -d 900

       will, therefore, poll all the hosts described  in  your  ~/.fetchmailrc  file  (except  those  explicitly
       excluded  with  the  'skip' verb) a bit less often than once every 15 minutes (exactly: 15 minutes + time
       that the poll takes).

       It  is  also  possible  to  set  a   polling   interval   in   your   ~/.fetchmailrc   file   by   saying
       'set daemon <interval>',  where  <interval>  is  an integer number of seconds.  If you do this, fetchmail
       will always start in daemon mode unless you override it with the command-line option --daemon 0 or -d0.

       Only one daemon process is permitted per user; in daemon mode, fetchmail sets up a per-user lock file  to
       guarantee  this.   (You can however cheat and set the FETCHMAILHOME environment variable to overcome this
       setting, but in that case, it is your responsibility to make sure you are not  polling  the  same  server
       with two processes at the same time.)

   Awakening the background daemon
       Normally,  calling  fetchmail  with  a  daemon in the background sends a wake-up signal to the daemon and
       quits without output. The background daemon then starts its next poll  cycle  immediately.   The  wake-up
       signal,  SIGUSR1, can also be sent manually. The wake-up action also clears any 'wedged' flags indicating
       that connections have wedged due to failed authentication or multiple timeouts.

   Terminating the background daemon
       The option -q or --quit will kill a running daemon process instead of waking it up (if there is  no  such
       process,  fetchmail  will  notify you).  If the --quit option appears last on the command line, fetchmail
       will kill the running daemon process and then quit. Otherwise, fetchmail will first kill a running daemon
       process and then continue running with the other options.

   Useful options for daemon mode
       The  -L <filename> or --logfile <filename> option (keyword: set logfile) is only effective when fetchmail
       is detached and in daemon mode. Note that the logfile must exist before fetchmail is run, you can use the
       touch(1) command with the filename as its sole argument to create it.
       This  option  allows you to redirect status messages into a specified logfile (follow the option with the
       logfile name).  The logfile is opened for  append,  so  previous  messages  are  not  deleted.   This  is
       primarily  useful  for  debugging  configurations.  Note that fetchmail does not detect if the logfile is
       rotated, the logfile is only opened once when fetchmail starts.  You  need  to  restart  fetchmail  after
       rotating the logfile and before compressing it (if applicable).

       The --syslog option (keyword: set syslog) allows you to redirect status and error messages emitted to the
       syslog(3) system daemon if available.  Messages  are  logged  with  an  id  of  fetchmail,  the  facility
       LOG_MAIL,  and priorities LOG_ERR, LOG_ALERT or LOG_INFO.  This option is intended for logging status and
       error messages which indicate the status of the daemon and the  results  while  fetching  mail  from  the
       server(s).   Error  messages for command line options and parsing the .fetchmailrc file are still written
       to stderr, or to the specified log file.  The --nosyslog option turns off use of syslog(3),  assuming  it
       is  turned on in the ~/.fetchmailrc file.  This option is overridden, in certain situations, by --logfile
       (which see).

       The -N or --nodetach option suppresses backgrounding and  detachment  of  the  daemon  process  from  its
       control  terminal.   This  is  useful  for  debugging or when fetchmail runs as the child of a supervisor
       process such as init(8) or Gerrit Pape's runit(8).  Note that this also causes the logfile option  to  be
       ignored.

       Note  that  while running in daemon mode polling a POP2 or IMAP2bis server, transient errors (such as DNS
       failures or sendmail delivery refusals) may force the fetchall option on for the  duration  of  the  next
       polling  cycle.   This  is  a robustness feature.  It means that if a message is fetched (and thus marked
       seen by the mail server) but not delivered locally due to some transient error,  it  will  be  re-fetched
       during  the  next poll cycle.  (The IMAP logic does not delete messages until they are delivered, so this
       problem does not arise.)

       If you touch or change the ~/.fetchmailrc file while fetchmail is running in daemon mode,  this  will  be
       detected  at  the beginning of the next poll cycle.  When a changed ~/.fetchmailrc is detected, fetchmail
       rereads it and restarts from scratch (using  exec(2);  no  state  information  is  retained  in  the  new
       instance).   Note that if fetchmail needs to query for passwords, of that if you break the ~/.fetchmailrc
       file's syntax, the new instance will softly and silently vanish away on startup.

ADMINISTRATIVE OPTIONS

       The --postmaster <name> option (keyword: set postmaster) specifies  the  last-resort  username  to  which
       multidrop  mail  is  to  be  forwarded  if  no  matching local recipient can be found. It is also used as
       destination of undeliverable mail if the 'bouncemail' global option is off  and  additionally  for  spam-
       blocked  mail  if  the  'bouncemail'  global option is off and the 'spambounce' global option is on. This
       option defaults to the user who invoked fetchmail.  If the invoking user is root,  then  the  default  of
       this  option  is  the  user  'postmaster'.   Setting  postmaster  to the empty string causes such mail as
       described above to be discarded - this however is usually a bad idea.  See also the  description  of  the
       'FETCHMAILUSER' environment variable in the ENVIRONMENT section below.

       The --nobounce behaves like the "set no bouncemail" global option, which see.

       The  --invisible  option (keyword: set invisible) tries to make fetchmail invisible.  Normally, fetchmail
       behaves like any other MTA would -- it generates a Received header into each message describing its place
       in  the  chain  of  transmission,  and  tells  the MTA it forwards to that the mail came from the machine
       fetchmail itself is running on.  If the invisible option is on, the Received  header  is  suppressed  and
       fetchmail tries to spoof the MTA it forwards to into thinking it came directly from the mail server host.

       The  --showdots  option (keyword: set showdots) forces fetchmail to show progress dots even if the output
       goes to a file or fetchmail is not in verbose mode.  Fetchmail shows the dots  by  default  when  run  in
       --verbose mode and output goes to console. This option is ignored in --silent mode.

       By specifying the --tracepolls option, you can ask fetchmail to add information to the Received header on
       the form "polling {label} account {user}", where {label} is the account label (from the specified rcfile,
       normally  ~/.fetchmailrc)  and  {user}  is  the username which is used to log on to the mail server. This
       header can be used to make filtering email where no useful header information is available and  you  want
       mail  from different accounts sorted into different mailboxes (this could, for example, occur if you have
       an account on the same server running a mailing list, and are subscribed to the list using that account).
       The default is not adding any such header.  In .fetchmailrc, this is called 'tracepolls'.

RETRIEVAL FAILURE MODES

       The  protocols  fetchmail  uses  to  talk  to  mail servers are next to bulletproof.  In normal operation
       forwarding to port 25, no message is ever deleted (or even marked for deletion) on  the  host  until  the
       SMTP  listener on the client side has acknowledged to fetchmail that the message has been either accepted
       for delivery or rejected due to a spam block.

       When forwarding to an MDA, however, there is more  possibility  of  error.   Some  MDAs  are  'safe'  and
       reliably  return  a nonzero status on any delivery error, even one due to temporary resource limits.  The
       maildrop(1) program is like this; so are most  programs  designed  as  mail  transport  agents,  such  as
       sendmail(1),  including the sendmail wrapper of Postfix and exim(1).  These programs give back a reliable
       positive acknowledgement and can be used with the mda option with no risk of  mail  loss.   Unsafe  MDAs,
       though, may return 0 even on delivery failure.  If this happens, you will lose mail.

       The normal mode of fetchmail is to try to download only 'new' messages, leaving untouched (and undeleted)
       messages you have already read directly on the server (or fetched with a previous fetchmail --keep).  But
       you  may find that messages you have already read on the server are being fetched (and deleted) even when
       you do not specify --all.  There are several reasons this can happen.

       One could be that you are using POP2.  The POP2 protocol includes no representation  of  'new'  or  'old'
       state  in  messages,  so fetchmail must treat all messages as new all the time.  But POP2 is obsolete, so
       this is unlikely.

       A potential POP3 problem might be servers that insert messages in  the  middle  of  mailboxes  (some  VMS
       implementations  of  mail  are  rumored  to  do  this).  The fetchmail code assumes that new messages are
       appended to the end of the mailbox; when this is not true it may treat some old messages as new and  vice
       versa.  Using UIDL whilst setting fastuidl 0 might fix this, otherwise, consider switching to IMAP.

       Yet  another  POP3 problem is that if they cannot make temporary files in the user's home directory, some
       POP3 servers will hand back an undocumented response that  causes  fetchmail  to  spuriously  report  "No
       mail".

       The IMAP code uses the presence or absence of the server flag \Seen to decide whether or not a message is
       new.  This is not the right thing to do, fetchmail should check the UIDVALIDITY and use UID, but it  does
       not  do  that  yet. Under Unix, it counts on your IMAP server to notice the BSD-style Status flags set by
       mail user agents and set the \Seen flag from them when appropriate.  All Unix IMAP servers we know of  do
       this,  though  it  is  not specified by the IMAP RFCs.  If you ever trip over a server that does not, the
       symptom will be that messages you have already read on your host will look new to the  server.   In  this
       (unlikely) case, only messages you fetched with fetchmail --keep will be both undeleted and marked old.

       In ETRN and ODMR modes, fetchmail does not actually retrieve messages; instead, it asks the server's SMTP
       listener to start a queue flush to the client via SMTP.  Therefore it sends only undelivered messages.

SPAM FILTERING

       Many SMTP listeners allow administrators to set up 'spam  filters'  that  block  unsolicited  email  from
       specified  domains.   A  MAIL  FROM  or DATA line that triggers this feature will elicit an SMTP response
       which (unfortunately) varies according to the listener.

       Newer versions of sendmail return an error code of 571.

       According to RFC2821, the correct thing to return in this situation is 550 "Requested action  not  taken:
       mailbox unavailable" (the draft adds "[E.g., mailbox not found, no access, or command rejected for policy
       reasons].").

       Older versions of the exim MTA return 501 "Syntax error in parameters or arguments".

       The postfix MTA runs 554 as an antispam response.

       Zmailer may reject code with a 500 response (followed by an  enhanced  status  code  that  contains  more
       information).

       Return  codes  which  fetchmail treats as antispam responses and discards the message can be set with the
       'antispam' option.  This is one of the only three circumstance under which fetchmail ever  discards  mail
       (the  others  are  the  552 and 553 errors described below, and the suppression of multi-dropped messages
       with a message-ID already seen).

       If fetchmail is fetching from an IMAP server, the antispam response will  be  detected  and  the  message
       rejected  immediately  after  the headers have been fetched, without reading the message body.  Thus, you
       will not pay for downloading spam message bodies.

       By default, the list of antispam responses is empty.

       If the spambounce global option is on, mail that  is  spam-blocked  triggers  an  RFC1892/RFC1894  bounce
       message informing the originator that we do not accept mail from it. See also BUGS.

SMTP/ESMTP ERROR HANDLING

       Besides  the spam-blocking described above, fetchmail takes special actions — that may be modified by the
       --softbounce option — on the following SMTP/ESMTP error response codes

       452 (insufficient system storage)
            Leave the message in the server mailbox for later retrieval.

       552 (message exceeds fixed maximum message size)
            Delete the message from the server.  Send bounce-mail to the originator.

       553 (invalid sending domain)
            Delete the message from the server.  Do not even try to send bounce-mail to the originator.

       Other errors greater or equal to 500 trigger bounce mail back to the  originator,  unless  suppressed  by
       --softbounce. See also BUGS.

THE RUN CONTROL FILE

       The  preferred way to set up fetchmail is to write a .fetchmailrc file in your home directory (you may do
       this directly, with a text editor, or indirectly via fetchmailconf).  When there is  a  conflict  between
       the command-line arguments and the arguments in this file, the command-line arguments take precedence.

       To  protect  the  security  of  your  passwords, your ~/.fetchmailrc may not normally have more than 0700
       (u=rwx,g=,o=) permissions; fetchmail will complain and exit otherwise  (this  check  is  suppressed  when
       --version is on).

       You  may read the .fetchmailrc file as a list of commands to be executed when fetchmail is called with no
       arguments.

   Run Control Syntax
       Comments begin with a '#' and extend through the end of the line.   Otherwise  the  file  consists  of  a
       series of server entries or global option statements in a free-format, token-oriented syntax.

       There  are  four  kinds  of  tokens:  grammar keywords, numbers (i.e., decimal digit sequences), unquoted
       strings, and quoted strings.  A quoted string is bounded by double quotes and may contain whitespace (and
       quoted  digits are treated as a string).  Note that quoted strings will also contain line feed characters
       if they run across two or more lines, unless you use a backslash to join lines (see below).  An  unquoted
       string  is any whitespace-delimited token that is neither numeric, string quoted nor contains the special
       characters ',', ';', ':', or '='.

       Any amount of whitespace separates tokens in server entries,  but  is  otherwise  ignored.  You  may  use
       backslash  escape  sequences  (\n  for  LF,  \t for HT, \b for BS, \r for CR, \nnn for decimal (where nnn
       cannot start with a 0), \0ooo for octal, and \xhh for hex) to embed non-printable  characters  or  string
       delimiters in strings.  In quoted strings, a backslash at the very end of a line will cause the backslash
       itself and the line feed (LF or NL, new line) character to be ignored, so that you can wrap long strings.
       Without the backslash at the line end, the line feed character would become part of the string.

       Warning:  while  these resemble C-style escape sequences, they are not the same.  fetchmail only supports
       these eight styles. C supports more  escape  sequences  that  consist  of  backslash  (\)  and  a  single
       character,  but  does  not  support  decimal  codes and does not require the leading 0 in octal notation.
       Example: fetchmail interprets \233 the same as \xE9 (Latin small letter e  with  acute),  where  C  would
       interpret \233 as octal 0233 = \x9B (CSI, control sequence introducer).

       Each  server  entry consists of one of the keywords 'poll' or 'skip', followed by a server name, followed
       by server options, followed by any number of user (or username) descriptions, followed by  user  options.
       Note: the most common cause of syntax errors is mixing up user and server options or putting user options
       before the user descriptions.

       For backward compatibility, the word 'server' is a synonym for 'poll'.

       You can use the noise keywords 'and', 'with', 'has', 'wants', and 'options' anywhere in an entry to  make
       it  resemble  English.   They  are  ignored,  but  can make entries much easier to read at a glance.  The
       punctuation characters ':', ';' and ',' are also ignored.

   Poll versus Skip
       The 'poll' verb tells fetchmail to query this host when it is run with no  arguments.   The  'skip'  verb
       tells  fetchmail  not  to  poll this host unless it is explicitly named on the command line.  (The 'skip'
       verb allows you to experiment with test entries safely, or easily disable  entries  for  hosts  that  are
       temporarily down.)

KEYWORD/OPTION SUMMARY

       Here  are  the  legal  options.   Keyword  suffixes  enclosed  in  square  brackets  are optional.  Those
       corresponding to short command-line options are followed by '-' and the appropriate  option  letter.   If
       option  is  only  relevant  to  a  single mode of operation, it is noted as 's' or 'm' for singledrop- or
       multidrop-mode, respectively.

       Here are the legal global options:

       Keyword             Opt   Mode   Function
       ────────────────────────────────────────────────────────────────────
       set daemon          -d           Set a background poll interval  in
                                        seconds.
       set postmaster                   Give  the  name of the last-resort
                                        mail  recipient   (default:   user
                                        running fetchmail, "postmaster" if
                                        run by the root user)
       set    bouncemail                Direct error mail  to  the  sender
                                        (default)
       set no bouncemail                Direct  error  mail  to  the local
                                        postmaster     (as     per     the
                                        'postmaster' global option above).
       set no spambounce                Do  not  bounce  spam-blocked mail
                                        (default).
       set    spambounce                Bounce blocked  spam-blocked  mail
                                        (as   per   the   'antispam'  user
                                        option) back to the destination as
                                        indicated   by   the  'bouncemail'
                                        global option.   Warning:  Do  not
                                        use  this  to  bounce spam back to
                                        the sender -  most  spam  is  sent
                                        with false sender address and thus
                                        this   option    hurts    innocent
                                        bystanders.

       set no softbounce                Delete  permanently  undeliverable
                                        mail. It  is  recommended  to  use
                                        this  option  if the configuration
                                        has been thoroughly tested.
       set    softbounce                Keep   permanently   undeliverable
                                        mail  as  though a temporary error
                                        had occurred (default).
       set logfile         -L           Name of a file to append error and
                                        status    messages    to.     Only
                                        effective in daemon  mode  and  if
                                        fetchmail detaches.  If effective,
                                        overrides set syslog.
       set pidfile         -p           Name of the PID file.
       set idfile          -i           Name of  the  file  to  store  UID
                                        lists in.
       set    syslog                    Do     error    logging    through
                                        syslog(3). May  be  overridden  by
                                        set logfile.
       set no syslog                    Turn  off  error  logging  through
                                        syslog(3). (default)
       set properties                   String value that  is  ignored  by
                                        fetchmail    (may   be   used   by
                                        extension scripts).

       Here are the legal server options:

       Keyword          Opt   Mode   Function
       ─────────────────────────────────────────────────────────────────
       via                           Specify DNS name of  mail  server,
                                     overriding poll name
       proto[col]       -p           Specify       protocol       (case
                                     insensitive):  POP2,  POP3,  IMAP,
                                     APOP, KPOP
       local[domains]         m      Specify  domain(s)  to be regarded
                                     as local
       port                          Specify   TCP/IP   service    port
                                     (obsolete, use 'service' instead).
       service          -P           Specify  service  name  (a numeric
                                     value   is   also   allowed    and
                                     considered a TCP/IP port number).
       auth[enticate]                Set  authentication  type (default
                                     'any')
       timeout          -t           Server   inactivity   timeout   in
                                     seconds (default 300)
       envelope         -E    m      Specify   envelope-address  header
                                     name
       no envelope            m      Disable   looking   for   envelope
                                     address
       qvirtual         -Q    m      Qmail  virtual  domain  prefix  to
                                     remove from user name
       aka                    m      Specify  alternate  DNS  names  of
                                     mail server
       interface        -I           specify  IP interface(s) that must
                                     be up  for  server  poll  to  take
                                     place
       monitor          -M           Specify  IP address to monitor for
                                     activity
       plugin                        Specify command through  which  to
                                     make server connections.
       plugout                       Specify  command  through which to
                                     make listener connections.
       dns                    m      Enable DNS  lookup  for  multidrop
                                     (default)
       no dns                 m      Disable DNS lookup for multidrop
       checkalias             m      Do  comparison  by  IP address for
                                     multidrop

       no checkalias          m      Do   comparison   by   name    for
                                     multidrop (default)
       uidl             -U           Force   POP3  to  use  client-side
                                     UIDLs (recommended)
       no uidl                       Turn off POP3 use  of  client-side
                                     UIDLs (default)
       interval                      Only  check this site every N poll
                                     cycles; N is a numeric argument.
       tracepolls                    Add poll  tracing  information  to
                                     the Received header
       principal                     Set   Kerberos   principal   (only
                                     useful with IMAP and kerberos)
       esmtpname                     Set     name      for      RFC2554
                                     authentication    to   the   ESMTP
                                     server.
       esmtppassword                 Set    password    for     RFC2554
                                     authentication    to   the   ESMTP
                                     server.
       bad-header                    How to treat messages with  a  bad
                                     header. Can be reject (default) or
                                     accept.

       Here are the legal user descriptions and options:

       Keyword            Opt   Mode                     Function
       ─────────────────────────────────────────────────────────────────────────────────────
       user[name]         -u                             This is the user  description  and
                                                         must   come   first  after  server
                                                         description  and  after   possible
                                                         server  options,  and  before user
                                                         options.

                                                         It sets the remote user name if by
                                                         itself  or followed by 'there', or
                                                         the local user name if followed by
                                                         'here'.
       is                                                Connect   local  and  remote  user
                                                         names
       to                                                Connect  local  and  remote   user
                                                         names
       pass[word]                                        Specify remote account password
       ssl                                               Connect   to   server   over   the
                                                         specified base protocol using  SSL
                                                         encryption
       sslcert                                           Specify   file   for  client  side
                                                         public SSL certificate
       sslcertck                                         Enable strict certificate checking
                                                         and  abort  connection on failure.
                                                         Default   only   since   fetchmail
                                                         v6.4.0.
       no sslcertck                                      Disable     strict     certificate
                                                         checking and permit connections to
                                                         continue  on  failed verification.
                                                         Discouraged. Should only  be  used
                                                         together with sslfingerprint.
       sslcertfile                                       Specify   file   with  trusted  CA
                                                         certificates
       sslcertpath                                       Specify c_rehash-ed directory with
                                                         trusted CA certificates.
       sslfingerprint           Specify  the  expected
                                server     certificate
                                finger  print  from an
                                MD5  hash.   Fetchmail
                                will   disconnect  and
                                log  an  error  if  it
                                does not match.

       sslkey                                            Specify   file   for  client  side
                                                         private SSL key
       sslproto                                          Force ssl protocol for connection
       folder             -r                             Specify remote folder to query
       smtphost           -S                             Specify smtp host(s) to forward to
       fetchdomains             m                        Specify  domains  for  which  mail
                                                         should be fetched
       smtpaddress        -D                             Specify  the  domain  to be put in
                                                         RCPT TO lines
       smtpname                                          Specify the user and domain to  be
                                                         put in RCPT TO lines
       antispam           -Z                             Specify   what  SMTP  returns  are
                                                         interpreted as spam-policy blocks
       mda                -m                             Specify MDA for local delivery
       bsmtp                                             Specify BSMTP batch file to append
                                                         to
       preconnect                                        Command to be executed before each
                                                         connection
       postconnect                                       Command to be executed after  each
                                                         connection
       keep               -k                             Do  not  delete seen messages from
                                                         server   (for   POP3,   uidl    is
                                                         recommended)
       flush              -F                             Flush  all  seen  messages  before
                                                         querying (DANGEROUS)
       limitflush                                        Flush   all   oversized   messages
                                                         before querying
       fetchall           -a                             Fetch all messages whether seen or
                                                         not
       rewrite                                           Rewrite destination addresses  for
                                                         reply (default)
       stripcr                                           Strip  carriage  returns from ends
                                                         of lines
       forcecr                                           Force carriage returns at ends  of
                                                         lines
       pass8bits                                         Force   BODY=8BITMIME   to   ESMTP
                                                         listener
       dropstatus                                        Strip Status and  X-Mozilla-Status
                                                         lines out of incoming mail
       dropdelivered                                     Strip  Delivered-To  lines  out of
                                                         incoming mail
       mimedecode                                        Convert quoted-printable to  8-bit
                                                         in MIME messages
       idle                                              Idle   waiting  for  new  messages
                                                         after each poll (IMAP only)
       no keep            -K                             Delete seen messages  from  server
                                                         (default)
       no flush                                          Do  not  flush  all  seen messages
                                                         before querying (default)
       no fetchall                                       Retrieve   only    new    messages
                                                         (default)
       no rewrite                                        Do not rewrite headers
       no stripcr                                        Do   not  strip  carriage  returns
                                                         (default)
       no forcecr                                        Do not force carriage  returns  at
                                                         EOL (default)
       no pass8bits                                      Do   not  force  BODY=8BITMIME  to
                                                         ESMTP listener (default)
       no dropstatus                                     Do   not   drop   Status   headers
                                                         (default)
       no dropdelivered                                  Do  not  drop Delivered-To headers
                                                         (default)
       no mimedecode                                     Do not convert quoted-printable to
                                                         8-bit in MIME messages (default)
       no idle                                           Do   not   idle  waiting  for  new
                                                         messages  after  each  poll  (IMAP
                                                         only)
       limit              -l                             Set message size limit

       warnings           -w                             Set message size warning interval
       batchlimit         -b                             Max   #  messages  to  forward  in
                                                         single connect
       fetchlimit         -B                             Max # messages to fetch in  single
                                                         connect
       fetchsizelimit                                    Max  #  message  sizes to fetch in
                                                         single transaction
       fastuidl                                          Use binary search for first unseen
                                                         message (POP3 only)
       expunge            -e                             Perform  an  expunge  on every #th
                                                         message (IMAP and POP3 only)
       properties                                        String   value   is   ignored   by
                                                         fetchmail    (may   be   used   by
                                                         extension scripts)

       All user options must begin with a user description (user or  username  option)  and  follow  all  server
       descriptions and options.

       In  the  .fetchmailrc  file,  the  'envelope'  string  argument may be preceded by a whitespace-separated
       number.  This number, if specified, is the number of such headers to skip over (that is, an argument of 1
       selects  the  second  header  of  the  given type).  This is sometimes useful for ignoring bogus envelope
       headers created by an ISP's local delivery agent or internal forwards (through mail  inspection  systems,
       for instance).

   Keywords Not Corresponding To Option Switches
       The  'folder'  and 'smtphost' options (unlike their command-line equivalents) can take a space- or comma-
       separated list of names following them.

       All options correspond to the obvious command-line arguments, except the  following:  'via',  'interval',
       'aka', 'is', 'to', 'dns'/'no dns', 'checkalias'/'no checkalias', 'password', 'preconnect', 'postconnect',
       'localdomains', 'stripcr'/'no stripcr', 'forcecr'/'no forcecr', 'pass8bits'/'no pass8bits' 'dropstatus/no
       dropstatus', 'dropdelivered/no dropdelivered', 'mimedecode/no mimedecode', 'no idle', and 'no envelope'.

       The 'via' option is for if you want to have more than one configuration pointing at the same site.  If it
       is present, the string argument will be taken as the actual DNS name of the mail server  host  to  query.
       This  will override the argument of poll, which can then simply be a distinct label for the configuration
       (e.g., what you would give on the command line to explicitly query this host).

       The 'interval' option (which takes a numeric argument) allows you to poll a server less  frequently  than
       the  basic  poll  interval.   If  you say 'interval N' the server this option is attached to will only be
       queried every N poll intervals.

   Singledrop versus Multidrop options
       Please ensure you read the section titled THE USE AND ABUSE OF MULTIDROP MAILBOXES if you intend  to  use
       multidrop mode.

       The  'is'  or 'to' keywords associate the following local (client) name(s) (or server-name to client-name
       mappings separated by =) with the mail server user name in the entry.  If an is/to list has  '*'  as  its
       last  name,  unrecognized  names  are  simply  passed  through.  Note  that until fetchmail version 6.3.4
       inclusively, these lists could only contain local parts of user names (fetchmail would only look  at  the
       part  before the @ sign). fetchmail versions 6.3.5 and newer support full addresses on the left hand side
       of these mappings, and they take precedence over any 'localdomains', 'aka', 'via' or similar mappings.

       A single local name can be used to support redirecting your mail when your username on the client machine
       is  different  from  your  name  on  the  mail  server.   When there is only a single local name, mail is
       forwarded to that local username regardless of the message's Received, To, Cc, and Bcc headers.  In  this
       case, fetchmail never does DNS lookups.

       When  there  is  more  than  one local name (or name mapping), fetchmail looks at the envelope header, if
       configured, and otherwise at the Received, To, Cc, and Bcc headers of retrieved mail (this is  'multidrop
       mode').   It  looks  for addresses with host name parts that match your poll name or your 'via', 'aka' or
       'localdomains' options, and usually also for host name parts which DNS tells it are aliases of  the  mail
       server.  See the discussion of 'dns', 'checkalias', 'localdomains', and 'aka' for details on how matching
       addresses are handled.

       If fetchmail cannot match any mail server usernames or localdomain addresses, the mail will  be  bounced.
       Normally it will be bounced to the sender, but if the 'bouncemail' global option is off, the mail will go
       to the local postmaster instead.  (see the 'postmaster' global option). See also BUGS.

       The 'dns' option (normally on) controls the way addresses from multidrop mailboxes are checked.   On,  it
       enables  logic  to  check each host address that does not match an 'aka' or 'localdomains' declaration by
       looking it up with DNS.  When a mail server username is recognized attached to a matching host name part,
       its local mapping is added to the list of local recipients.

       The  'checkalias'  option  (normally off) extends the lookups performed by the 'dns' keyword in multidrop
       mode, providing a way to cope with remote MTAs that identify themselves using their canonical name, while
       they  are  polled  using  an alias.  When such a server is polled, checks to extract the envelope address
       fail, and fetchmail reverts to delivery using the To/Cc/Bcc headers (See below  'Header  versus  Envelope
       addresses').  Specifying this option instructs fetchmail to retrieve all the IP addresses associated with
       both the poll name and the name used by the remote MTA and to do a comparison of the IP addresses.   This
       comes  in  handy  in  situations  where the remote server undergoes frequent canonical name changes, that
       would otherwise require modifications to the rcfile.  'checkalias' has no effect if 'no dns' is specified
       in the rcfile.

       The 'aka' option is for use with multidrop mailboxes.  It allows you to pre-declare a list of DNS aliases
       for a server.  This is an optimization hack that allows you to trade space for  speed.   When  fetchmail,
       while  processing  a  multidrop  mailbox,  grovels  through message headers looking for names of the mail
       server, pre-declaring common ones can save it from having to do DNS lookups.  Note: the names you give as
       arguments  to 'aka' are matched as suffixes -- if you specify (say) 'aka netaxs.com', this will match not
       just  a  host  name  netaxs.com,  but  any  host  name  that  ends  with  '.netaxs.com';  such  as  (say)
       pop3.netaxs.com and mail.netaxs.com.

       The  'localdomains' option allows you to declare a list of domains which fetchmail should consider local.
       When fetchmail is parsing address lines in multidrop modes, and a trailing segment of a host name matches
       a  declared  local  domain,  that  address is passed through to the listener or MDA unaltered (local-name
       mappings are not applied).

       If you are using 'localdomains', you may also need to specify 'no envelope', which  disables  fetchmail's
       normal  attempt  to deduce an envelope address from the Received line or X-Envelope-To header or whatever
       header has been previously set by 'envelope'.  If you set 'no envelope'  in  the  defaults  entry  it  is
       possible  to  undo that in individual entries by using 'envelope <string>'.  As a special case, 'envelope
       "Received"' restores the default parsing of Received lines.

       The password option requires a string argument, which is the password to be used with the entry's server.

       The 'preconnect' keyword allows you to specify a shell command to  be  executed  just  before  each  time
       fetchmail  establishes  a  mail  server  connection.   This may be useful if you are attempting to set up
       secure POP connections with the aid of ssh(1).  If the command returns a nonzero status, the poll of that
       mail server will be aborted.

       Similarly,  the 'postconnect' keyword similarly allows you to specify a shell command to be executed just
       after each time a mail server connection is taken down.

       The 'forcecr' option controls whether lines terminated by LF  only  are  given  CRLF  termination  before
       forwarding.   Strictly speaking RFC821 requires this, but few MTAs enforce the requirement so this option
       is normally off (only one such MTA, qmail, is in significant use at time of writing).

       The 'stripcr' option controls whether carriage returns are stripped out of retrieved mail  before  it  is
       forwarded.   It is normally not necessary to set this, because it defaults to 'on' (CR stripping enabled)
       when there is an MDA declared but 'off'  (CR  stripping  disabled)  when  forwarding  is  via  SMTP.   If
       'stripcr' and 'forcecr' are both on, 'stripcr' will override.

       The  'pass8bits'  option  exists  to  cope  with  Microsoft  mail programs that stupidly slap a "Content-
       Transfer-Encoding: 7bit" on everything.  With this option off (the default) and such  a  header  present,
       fetchmail  declares  BODY=7BIT  to  an ESMTP-capable listener; this causes problems for messages actually
       using 8-bit ISO or KOI-8 character sets, which will be garbled by having the high bits of all  characters
       stripped.   If  'pass8bits'  is  on,  fetchmail  is  forced to declare BODY=8BITMIME to any ESMTP-capable
       listener.  If the listener is 8-bit-clean (as all the major ones now are) the right thing  will  probably
       result.

       The  'dropstatus'  option  controls  whether  nonempty  Status and X-Mozilla-Status lines are retained in
       fetched mail (the default) or discarded.  Retaining them allows your MUA to see what  messages  (if  any)
       were  marked seen on the server.  On the other hand, it can confuse some new-mail notifiers, which assume
       that anything with a Status line in it has been seen.  (Note: the empty Status  lines  inserted  by  some
       buggy POP servers are unconditionally discarded.)

       The  'dropdelivered'  option  controls  whether  Delivered-To  headers  will be kept in fetched mail (the
       default) or discarded. These headers are added by qmail and Postfix mail servers in order to  avoid  mail
       loops  but  may  get  in  your  way if you try to "mirror" a mail server within the same domain. Use with
       caution.

       The  'mimedecode'  option  controls  whether  MIME  messages  using  the  quoted-printable  encoding  are
       automatically converted into pure 8-bit data. If you are delivering mail to an ESMTP-capable, 8-bit-clean
       listener (that includes all of the major MTAs  like  sendmail),  then  this  will  automatically  convert
       quoted-printable  message  headers  and data into 8-bit data, making it easier to understand when reading
       mail. If your e-mail programs know how to deal with MIME messages, then this option is not  needed.   The
       mimedecode  option  is off by default, because doing RFC2047 conversion on headers throws away character-
       set information and can lead to bad results if  the  encoding  of  the  headers  differs  from  the  body
       encoding.

       The 'idle' option is intended to be used with IMAP servers supporting the RFC2177 IDLE command extension,
       but does not strictly require it.  If it is enabled, and fetchmail detects that  IDLE  is  supported,  an
       IDLE  will be issued at the end of each poll.  This will tell the IMAP server to hold the connection open
       and notify the client when new mail is available.  If IDLE is not supported, fetchmail will  simulate  it
       by  periodically  issuing  NOOP.  If  you  need  to  poll  a  link frequently, IDLE can save bandwidth by
       eliminating TCP/IP connects and LOGIN/LOGOUT sequences. On the other hand, an IDLE  connection  will  eat
       almost  all  of your fetchmail's time, because it will never drop the connection and allow other polls to
       occur unless the server times out the IDLE.  It also does not work with multiple folders; only the  first
       folder will ever be polled.

       The  'properties'  option  is  an  extension  mechanism.  It takes a string argument, which is ignored by
       fetchmail itself.  The string argument may be used to store configuration information for  scripts  which
       require  it.   In  particular, the output of '--configdump' option will make properties associated with a
       user entry readily available to a Python script.

   Miscellaneous Run Control Options
       The words 'here' and 'there' have useful English-like significance.  Normally 'user eric  is  esr'  would
       mean  that  mail for the remote user 'eric' is to be delivered to 'esr', but you can make this clearer by
       saying 'user eric there is esr here', or reverse it by saying 'user esr here is eric there'

       Legal protocol identifiers for use with the 'protocol' keyword are:

           auto (or AUTO) (legacy, to be removed from future release)
           pop2 (or POP2) (legacy, to be removed from future release)
           pop3 (or POP3)
           sdps (or SDPS)
           imap (or IMAP)
           apop (or APOP)
           kpop (or KPOP)

       Legal authentication types are 'any', 'password', 'kerberos', 'kerberos_v4', 'kerberos_v5' and  'gssapi',
       'cram-md5',  'otp',  'msn'  (only  for POP3), 'ntlm', 'ssh', 'external' (only IMAP).  The 'password' type
       specifies authentication by normal transmission of a password (the password may be plain text or  subject
       to  protocol-specific  encryption  as  in  CRAM-MD5); 'kerberos' tells fetchmail to try to get a Kerberos
       ticket at the start of each query instead, and send an arbitrary string as  the  password;  and  'gssapi'
       tells fetchmail to use GSSAPI authentication.  See the description of the 'auth' keyword for more.

       Specifying  'kpop' sets POP3 protocol over port 1109 with Kerberos V4 authentication.  These defaults may
       be overridden by later options.

       There are some global option statements: 'set  logfile'  followed  by  a  string  sets  the  same  global
       specified  by --logfile.  A command-line --logfile option will override this. Note that --logfile is only
       effective if fetchmail detaches itself from the terminal and the logfile already exists before  fetchmail
       is  run,  and  it overrides --syslog in this case.  Also, 'set daemon' sets the poll interval as --daemon
       does.  This can be overridden by a command-line --daemon option; in particular --daemon 0 can be used  to
       force  foreground  operation.  The  'set  postmaster'  statement sets the address to which multidrop mail
       defaults if there are no local matches.  Finally, 'set syslog' sends log messages to syslogd(8).

DEBUGGING FETCHMAIL

   Fetchmail crashing
       There are various ways in that fetchmail may "crash", i. e. stop operation suddenly and  unexpectedly.  A
       "crash"  usually  refers  to  an error condition that the software did not handle by itself. A well-known
       failure mode is the "segmentation fault" or "signal 11" or "SIGSEGV" or just "segfault" for short.  These
       can  be  caused by hardware or by software problems. Software-induced segfaults can usually be reproduced
       easily and in the same place, whereas hardware-induced segfaults can go away if the computer is rebooted,
       or  powered off for a few hours, and can happen in random locations even if you use the software the same
       way.

       For solving hardware-induced segfaults, find the faulty component and repair or replace  it.   The  Sig11
       FAQ ⟨https://www.bitwizard.nl/sig11/⟩ may help you with details.

       For solving software-induced segfaults, the developers may need a "stack backtrace".

   Enabling fetchmail core dumps
       By  default,  fetchmail  suppresses  core  dumps  as  these  might  contain passwords and other sensitive
       information. For debugging fetchmail crashes, obtaining a "stack backtrace" from a core dump is often the
       quickest  way  to  solve the problem, and when posting your problem on a mailing list, the developers may
       ask you for a "backtrace".

       1. To get useful backtraces, fetchmail needs to be installed without getting stripped of its  compilation
       symbols.   Unfortunately,  most  binary  packages  that  are  installed are stripped, and core files from
       symbol-stripped programs are worthless. So you may need to recompile fetchmail. On many systems, you  can
       type

               file `which fetchmail`

       to  find  out  if fetchmail was symbol-stripped or not. If yours was unstripped, fine, proceed, if it was
       stripped, you need to recompile the source code first. You do not usually need to  install  fetchmail  in
       order to debug it.

       2.  The  shell environment that starts fetchmail needs to enable core dumps. The key is the "maximum core
       (file) size" that can usually be configured with a tool named "limit" or "ulimit". See the  documentation
       for your shell for details. In the popular bash shell, "ulimit -Sc unlimited" will allow the core dump.

       3.  You  need  to  tell  fetchmail,  too,  to allow core dumps. To do this, run fetchmail with the -d0 -v
       options.  It is often easier to also add --nosyslog -N as well.

       Finally, you need to reproduce the crash. You can just start  fetchmail  from  the  directory  where  you
       compiled  it  by  typing  ./fetchmail,  so  the  complete  command line will start with ./fetchmail -Nvd0
       --nosyslog and perhaps list your other options.

       After the crash, run your debugger to obtain the core dump.  The debugger will often be GNU GDB, you  can
       then  type  (adjust paths as necessary) gdb ./fetchmail fetchmail.core and then, after GDB has started up
       and read all its files, type backtrace full, save the output (copy & paste will do, the backtrace will be
       read  by  a human) and then type quit to leave gdb.  Note: on some systems, the core files have different
       names, they might contain a number instead of the program name, or number and name, but it  will  usually
       have "core" as part of their name.

INTERACTION WITH RFC 822

       When  trying  to  determine  the originating address of a message, fetchmail looks through headers in the
       following order:

               Return-Path:
               Resent-Sender: (ignored if it does not contain an @ or !)
               Sender: (ignored if it does not contain an @ or !)
               Resent-From:
               From:
               Reply-To:
               Apparently-From:

       The originating address is used for logging, and to set the MAIL FROM address when  forwarding  to  SMTP.
       This  order  is  intended  to cope gracefully with receiving mailing list messages in multidrop mode. The
       intent is that if a local address does not exist, the bounce message will not be returned blindly to  the
       author or to the list itself, but rather to the list manager (which is less annoying).

       In  multidrop  mode,  destination headers are processed as follows: First, fetchmail looks for the header
       specified by the 'envelope' option in order to determine the local recipient  address.  If  the  mail  is
       addressed  to  more  than  one  recipient,  the  Received line will not contain any information regarding
       recipient addresses.

       Then fetchmail looks for the Resent-To:, Resent-Cc:, and Resent-Bcc: lines.  If they exist,  they  should
       contain  the  final recipients and have precedence over their To:/Cc:/Bcc: counterparts.  If the Resent-*
       lines do not exist, the To:, Cc:, Bcc: and Apparently-To: lines  are  looked  for.  (The  presence  of  a
       Resent-To:  is  taken  to  imply  that  the  person  referred by the To: address has already received the
       original copy of the mail.)

CONFIGURATION EXAMPLES

       Note that although there are password declarations in a good many of the examples below, this  is  mainly
       for illustrative purposes.  We recommend stashing account/password pairs in your $HOME/.netrc file, where
       they can be used not just by fetchmail but by ftp(1) and other programs.

       The basic format is:

              poll SERVERNAME protocol PROTOCOL username NAME password PASSWORD

       Example:

              poll pop.provider.net protocol pop3 username "jsmith" password "secret1"

       Or, using some abbreviations:

              poll pop.provider.net proto pop3 user "jsmith" password "secret1"

       Multiple servers may be listed:

              poll pop.provider.net proto pop3 user "jsmith" pass "secret1"
              poll other.provider.net proto pop2 user "John.Smith" pass "My^Hat"

       Here is the same version with more whitespace and some noise words:

              poll pop.provider.net proto pop3
                   user "jsmith", with password secret1, is "jsmith" here;
              poll other.provider.net proto pop2:
                   user "John.Smith", with password "My^Hat", is "John.Smith" here;

       If you need to include whitespace in a parameter string or start the latter with a  number,  enclose  the
       string in double quotes.  Thus:

              poll mail.provider.net with proto pop3:
                   user "jsmith" there has password "4u but u cannot krak this"
                   is jws here and wants mda "/bin/mail"

       You may have an initial server description headed by the keyword 'defaults' instead of 'poll' followed by
       a name.  Such a record is interpreted as defaults for all queries  to  use.  It  may  be  overwritten  by
       individual server descriptions.  So, you could write:

              defaults proto pop3
                   user "jsmith"
              poll pop.provider.net
                   pass "secret1"
              poll mail.provider.net
                   user "jjsmith" there has password "secret2"

       It  is  possible  to  specify  more  than  one  user  per  server.   The  'user' keyword leads off a user
       description, and every user specification in a multi-user entry must include it.  Here is an example:

              poll pop.provider.net proto pop3 port 3111
                   user "jsmith" with pass "secret1" is "smith" here
                   user jones with pass "secret2" is "jjones" here keep

       This associates the local username 'smith' with the pop.provider.net  username  'jsmith'  and  the  local
       username  'jjones'  with  the  pop.provider.net username 'jones'.  Mail for 'jones' is kept on the server
       after download.

       Here is what a simple retrieval configuration for a multidrop mailbox looks like:

              poll pop.provider.net:
                   user maildrop with pass secret1 to golux 'hurkle'='happy' snark here

       This says that the mailbox of account 'maildrop' on the server is a multidrop box, and that  messages  in
       it  should be parsed for the server user names 'golux', 'hurkle', and 'snark'.  It further specifies that
       'golux' and 'snark' have the same name on the client as on the server, but mail for server user  'hurkle'
       should be delivered to client user 'happy'.

       Note that fetchmail, until version 6.3.4, did NOT allow full user@domain specifications here, these would
       never match.  Fetchmail 6.3.5 and newer support user@domain specifications on the  left-hand  side  of  a
       user mapping.

       Here is an example of another kind of multidrop connection:

              poll pop.provider.net localdomains loonytoons.org toons.org
                   envelope X-Envelope-To
                   user maildrop with pass secret1 to * here

       This  also  says  that  the  mailbox  of  account  'maildrop' on the server is a multidrop box.  It tells
       fetchmail that any address in the loonytoons.org or toons.org  domains  (including  sub-domain  addresses
       like   'joe@daffy.loonytoons.org')   should  be  passed  through  to  the  local  SMTP  listener  without
       modification.  Be careful of mail loops if you do this!

       Here is an example configuration using ssh and the plugin option.  The queries are made directly  on  the
       stdin and stdout of imapd via ssh.  Note that in this setup, IMAP authentication can be skipped.

              poll mailhost.net with proto imap:
                   plugin "ssh %h /usr/sbin/imapd" auth ssh;
                   user esr is esr here

THE USE AND ABUSE OF MULTIDROP MAILBOXES

       Use  the  multiple-local-recipients  feature  with  caution  --  it can bite.  All multidrop features are
       ineffective in ETRN and ODMR modes.

       Also, note that in multidrop mode duplicate mails may be suppressed.   A  piece  of  mail  is  considered
       duplicate  if  it  does  not  have  a  discernible envelope recipient address, has the same header as the
       message immediately preceding and more than one addressee.  Such runs of messages may be  generated  when
       copies  of  a  message  addressed  to  multiple  users  are delivered to a multidrop box. (To be precise,
       fetchmail 6.2.5 through 6.4.X use an MD5 hash of the raw  message  header,  and  only  fetchmail  6.4.16+
       document  this  properly.   Fetchmail  5.0.8  (1999-09-14) through 6.2.4 used only the Message-ID header.
       5.0.7 and older did not suppress duplicates.)

       Note that this duplication killer code checking the  entire  header  is  very  restrictive  and  may  not
       suppress  many  duplicates  in  practice  -  for  instance,  if some X-Original-To or Delivered-To header
       differs.  This is intentional and correct in such situations: wherever envelope information is available,
       it  should  be  used  for reliable delivery of mailing list and blind carbon copy (Bcc) messages. See the
       subsection Duplicate suppression below for suggestions.

   Header versus Envelope addresses
       The fundamental problem is that by having your mail  server  toss  several  peoples'  mail  in  a  single
       maildrop  box,  you  may  have thrown away potentially vital information about who each piece of mail was
       actually addressed to (the 'envelope address', as opposed to the header addresses  in  the  RFC822  To/Cc
       headers  -  the  Bcc  is not available at the receiving end).  This 'envelope address' is the address you
       need in order to reroute mail properly.

       Sometimes fetchmail can deduce the envelope address.  If the mail server MTA is sendmail and the item  of
       mail  had  just  one  recipient,  the  MTA  will  have  written a 'by/for' clause that gives the envelope
       addressee into its Received header. But this does not work reliably for other MTAs, nor if there is  more
       than  one  recipient.  By default, fetchmail looks for envelope addresses in these lines; you can restore
       this default with -E "Received" or 'envelope Received'.

       As a better alternative, some SMTP listeners  and/or  mail  servers  insert  a  header  in  each  message
       containing  a  copy  of  the  envelope addresses.  This header (when it exists) is often 'X-Original-To',
       'Delivered-To' or 'X-Envelope-To'.  Fetchmail's assumption about this can  be  changed  with  the  -E  or
       'envelope'  option.   Note  that  writing an envelope header of this kind exposes the names of recipients
       (including blind-copy recipients) to all receivers of the messages, so the upstream must store  one  copy
       of the message per recipient to avoid becoming a privacy problem.

       Postfix,  since  version 2.0, writes an X-Original-To: header which contains a copy of the envelope as it
       was received.

       Qmail and Postfix generally write a 'Delivered-To' header upon delivering the message to the  mail  spool
       and  use  it  to avoid mail loops.  Qmail virtual domains however will prefix the user name with a string
       that normally matches the user's domain. To remove this prefix you can use the -Q or 'qvirtual' option.

       Sometimes, unfortunately, neither of these methods works.  That is the point when you should contact your
       ISP  and ask them to provide such an envelope header, and you should not use multidrop in this situation.
       When they all fail, fetchmail must fall back on the contents  of  To/Cc  headers  (Bcc  headers  are  not
       available  -  see  below)  to  try  to  determine  recipient  addressees -- and these are unreliable.  In
       particular, mailing-list software often ships mail with only  the  list  broadcast  address  in  the  To:
       header.

       Note that a future version of fetchmail may remove To/Cc parsing!

       When  fetchmail  cannot  deduce a recipient address that is local, and the intended recipient address was
       anyone other than fetchmail's invoking user, mail will get  lost.   This  is  what  makes  the  multidrop
       feature risky without proper envelope information.

       A  related  problem  is  that  when you blind-copy a mail message, the Bcc information is carried only as
       envelope address (it is removed from the headers by the sending mail server, so fetchmail can see it only
       if  there  is  an  X-Envelope-To  header).  Thus, blind-copying to someone who gets mail over a fetchmail
       multidrop link will fail unless the mail server host routinely  writes  X-Envelope-To  or  an  equivalent
       header into messages in your maildrop.

       In conclusion, mailing lists and Bcc'd mail can only work if the server you are fetching from

       (1)    stores one copy of the message per recipient in your domain and

       (2)    records the envelope information in a special header (X-Original-To, Delivered-To, X-Envelope-To).

   Good Ways To Use Multidrop Mailboxes
       Multiple  local  names  can  be  used  to  administer  a mailing list from the client side of a fetchmail
       collection.  Suppose your name is 'esr', and you want to both pick  up  your  own  mail  and  maintain  a
       mailing  list  called  (say)  "fetchmail-friends",  and  you  want  to keep the alias list on your client
       machine.

       On your server, you can alias 'fetchmail-friends' to 'esr'; then, in your .fetchmailrc, declare  'to  esr
       fetchmail-friends  here'.  Then, when mail including 'fetchmail-friends' as a local address gets fetched,
       the list name will be appended to the list of recipients your SMTP  listener  sees.   Therefore  it  will
       undergo   alias  expansion  locally.   Be  sure  to  include  'esr'  in  the  local  alias  expansion  of
       fetchmail-friends, or you will never see mail sent only to the list.  Also be sure that your listener has
       the  "me-too"  option  set  (sendmail's  -oXm command-line option or OXm declaration) so your name is not
       removed from alias expansions in messages you send.

       This trick is not without its problems, however.  You will begin to see this when a message comes in that
       is  addressed  only  to  a mailing list you do not have declared as a local name.  Each such message will
       feature an 'X-Fetchmail-Warning' header which is generated because fetchmail cannot find  a  valid  local
       name  in  the  recipient  addresses.  Such messages default (as was described above) to being sent to the
       local user running fetchmail, but the program has no way to know that this is actually the right thing.

   Bad Ways To Abuse Multidrop Mailboxes
       Multidrop mailboxes and fetchmail serving multiple users in daemon mode do not mix.  The problem,  again,
       is mail from mailing lists, which typically does not have an individual recipient address on it.   Unless
       fetchmail can deduce an envelope address, such mail  will  only  go  to  the  account  running  fetchmail
       (probably root).  Also, blind-copied users are very likely never to see their mail at all.

       If  you  are tempted to use fetchmail to retrieve mail for multiple users from a single mail drop via POP
       or IMAP, think again (and reread the section on header  and  envelope  addresses  above).   It  would  be
       smarter  to  just  let  the mail sit in the mail server's queue and use fetchmail's ETRN or ODMR modes to
       trigger SMTP sends periodically (of course, this means you have to poll more  frequently  than  the  mail
       server's expiry period).  If you cannot arrange this, try setting up a UUCP feed.

       If  you  absolutely  must  use multidrop for this purpose, make sure your mail server writes an envelope-
       address header that fetchmail can see.  Otherwise you will lose mail and it will come back to haunt you.

   Speeding Up Multidrop Checking
       Normally, when multiple users are declared fetchmail extracts recipient addresses as described above  and
       checks  each  host  part  with DNS to see if it is an alias of the mail server.  If so, the name mappings
       described in the "to ... here" declaration are done and the mail locally delivered.

       This is a convenient but also slow method.  To speed it up, pre-declare mail server aliases  with  'aka';
       these are checked before DNS lookups are done.  If you are certain your aka list contains all DNS aliases
       of the mail server (and all MX names pointing at it - note this may change in a future version)  you  can
       declare 'no dns' to suppress DNS lookups entirely and only match against the aka list.

   Duplicate suppression on multidrop
       If fetchmail's duplicate suppression code does not kick in for your multidrop mail account, other options
       is using sieve, or for instance Courier's maildrop package (and in particular, its reformail program with
       the  -D  option)  as  the  delivery  agent  (either  from  fetchmail, or from your local mail server that
       fetchmail injects into).

SOCKS

       Support for socks4/5 is a compile time configuration option. Once compiled in, fetchmail will always  use
       the  socks  libraries and configuration on your system, there are no run-time switches in fetchmail - but
       you can still configure SOCKS: you can specify which SOCKS configuration file is used in  the  SOCKS_CONF
       environment variable.

       For instance, if you wanted to bypass the SOCKS proxy altogether and have fetchmail connect directly, you
       could just pass SOCKS_CONF=/dev/null in the environment, for example (add your usual command line options
       - if any - to the end of this line):

       env SOCKS_CONF=/dev/null fetchmail

EXIT CODES

       To  facilitate  the  use  of  fetchmail  in  shell  scripts,  an  exit status code is returned to give an
       indication of what occurred during a given connection.

       The exit codes returned by fetchmail are as follows:

       0      One or more messages were successfully retrieved (or, if the -c option was  selected,  were  found
              waiting but not retrieved).

       1      There  was  no mail awaiting retrieval.  (There may have been old mail still on the server but not
              selected for retrieval.) If you do not want "no mail" to be an error condition (for instance,  for
              cron jobs), use a POSIX-compliant shell and add

              || [ $? -eq 1 ]

              to the end of the fetchmail command line, note that this leaves 0 untouched, maps 1 to 0, and maps
              all other codes to 1. See also item #C8 in the FAQ.

       2      An error was encountered when attempting to open a socket to retrieve mail.  If you  do  not  know
              what  a  socket  is,  do  not worry about it -- just treat this as an 'unrecoverable error'.  This
              error can also be because a protocol fetchmail wants to use is not listed in /etc/services.

       3      The user authentication step failed.  This usually means that a bad user-id, password, or APOP  id
              was  specified.   Or  it may mean that you tried to run fetchmail under circumstances where it did
              not have standard input attached to a terminal and could not prompt for a missing password.

       4      Some sort of fatal protocol error was detected.

       5      There was a syntax error in the arguments to fetchmail, or a pre- or post-connect command failed.

       6      The run control file had bad permissions.

       7      There was an error condition reported by the server.  Can also fire if fetchmail timed  out  while
              waiting for the server.

       8      Client-side  exclusion  error.   This  means fetchmail either found another copy of itself already
              running, or failed in such a way that it is not sure whether another copy is running.

       9      The user authentication step failed because the server responded "lock busy".  Try again  after  a
              brief  pause!   This  error  is  not  implemented  for all protocols, nor for all servers.  If not
              implemented for your server, "3" will be returned  instead,  see  above.   May  be  returned  when
              talking  to  qpopper  or  other  servers  that  can  respond with "lock busy" or some similar text
              containing the word "lock".

       10     The fetchmail run failed while trying to do an SMTP port open or transaction.

       11     Fatal DNS error.  Fetchmail encountered an error while performing a  DNS  lookup  at  startup  and
              could not proceed.

       12     BSMTP batch file could not be opened.

       13     Poll terminated by a fetch limit (see the --fetchlimit option).

       14     Server busy indication.

       23     Internal error.  You should see a message on standard error with details.

       24 - 26, 28, 29
              These are internal codes and should not appear externally.

       When  fetchmail  queries more than one host, return status is 0 if any query successfully retrieved mail.
       Otherwise the returned error status is that of the last host queried.

FILES

       ~/.fetchmailrc, $HOME/.fetchmailrc, $HOME_ETC/.fetchmailrc, $FETCHMAILHOME/fetchmailrc
            default run control file (location can be overridden with environment variables)

       ~/.fetchids, $HOME/.fetchids, $HOME_ETC/.fetchids, $FETCHMAILHOME/.fetchids
            default location of file recording last message UIDs seen per host.   (location  can  be  overridden
            with environment variables)

       ~/.fetchmail.pid, $HOME/.fetchmail.pid, $HOME_ETC/.fetchmail.pid, $FETCHMAILHOME/fetchmail.pid
            default  location  of  lock  file (sometimes called pidfile or PID file, see option pidfile) to help
            prevent concurrent runs (non-root mode).  (location can be overridden with environment variables)

       ~/.netrc, $HOME/.netrc, $HOME_ETC/.netrc
            your FTP run control file, which (if present) will be searched for passwords as a last resort before
            prompting for one interactively.  (location can be overridden with environment variables)

       /var/run/fetchmail.pid
            lock file (pidfile) to help prevent concurrent runs (root mode, Linux systems).

       /etc/fetchmail.pid
            lock file (pidfile) to help prevent concurrent runs (root mode, systems without /var/run).

ENVIRONMENT

       Fetchmail's  behavior  can  be  altered  by  providing it with environment variables.  Some may alter the
       operation of libraries that fetchmail links against, for instance, OpenSSL.  Note that  in  daemon  mode,
       you  will  need  to  quit  the background daemon process and start a new fetchmail daemon for environment
       changes to take effect.

       FETCHMAILHOME
              If this environment variable is set to a valid and existing directory name,  fetchmail  will  read
              $FETCHMAILHOME/fetchmailrc  (the  dot  is missing in this case), $FETCHMAILHOME/.fetchids (keeping
              its dot)  and  $FETCHMAILHOME/fetchmail.pid  (without  dot)  rather  than  from  the  user's  home
              directory.   The  .netrc  file  is  always  looked  for  in the invoking user's home directory (or
              $HOME_ETC) regardless of FETCHMAILHOME's setting.

       FETCHMAILUSER
              If this environment variable is set, it is used as the name of the  calling  user  (default  local
              name)  for purposes such as mailing error notifications.  Otherwise, if either the LOGNAME or USER
              variable is correctly set (e.g., the corresponding UID matches the session user ID) then that name
              is  used  as  the  default  local name.  Otherwise getpwuid(3) must be able to retrieve a password
              entry for the session ID (this elaborate logic is designed to handle the case  of  multiple  names
              per user ID gracefully).

       FETCHMAIL_DISABLE_CBC_IV_COUNTERMEASURE
              (since  v6.3.22):  If  this  environment  variable  is set and not empty, fetchmail will disable a
              countermeasure against an SSL CBC IV attack (by setting SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS).  This
              is  a  security  risk,  but  may  be  necessary for connecting to certain non-standards-conforming
              servers.  See fetchmail's NEWS file and fetchmail-SA-2012-01.txt for details.   Earlier  fetchmail
              versions  (v6.3.21 and older) used to disable this countermeasure, but v6.3.22 no longer does that
              as a safety precaution.

       FETCHMAIL_POP3_FORCE_RETR
              (since v6.3.9): If this environment variable is defined at all (even  if  empty),  fetchmail  will
              forgo the POP3 TOP command and always use RETR. This can be used as a workaround when TOP does not
              work properly.

       FETCHMAIL_INCLUDE_DEFAULT_X509_CA_CERTS
              (since v6.3.17): If this environment variable is set and not empty, fetchmail will always load the
              default X.509 trusted certificate locations for SSL/TLS CA certificates, even if --sslcertfile and
              --sslcertpath are given.  The latter locations take precedence over the system default  locations.
              This is useful in case there are broken certificates in the system directories and the user has no
              administrator privileges to remedy the problem.

       FETCHMAIL_WOLFSSL_DEBUG
              (since v6.4.25): If fetchmail is compiled and linked with  wolfSSL,  if  wolfSSL  was  built  with
              --enable-debug, and if this environment variable is set and not empty, then enable wolfSSL's debug
              mode. This will emit huge amounts of debug output to stderr.

       HOME   (documented since 6.4.1): This variable is normally set to the user's home directory. If it is set
              to a different directory than what is in the password database, HOME takes precedence.

       HOME_ETC
              (documentation corrected to match behaviour of code since 6.4.1): If the HOME_ETC variable is set,
              it will override fetchmail's idea of $HOME, i. e. fetchmail  will  read  .fetchmailrc,  .fetchids,
              .fetchmail.pid  and  .netrc  from  $HOME_ETC  instead of $HOME (or if HOME is also unset, from the
              passwd file's home directory location).

              If HOME_ETC and FETCHMAILHOME are both set, FETCHMAILHOME takes precedence and  HOME_ETC  will  be
              ignored.

       SOCKS_CONF
              (only  if  SOCKS  support  is  compiled in) this variable is used by the socks library to find out
              which configuration file it should read. Set this to /dev/null to bypass the SOCKS proxy.

       SSL_CERT_DIR
              (with truly OpenSSL 1.1.1 compatible library): overrides  OpenSSL's  idea  of  the  default  trust
              directory  or  path  (which  contains  individual  certificate files and hashed symlinks), see the
              SSL_CTX_set_default_verify_paths(3) manual page for details, it may be in the openssl  development
              package.   If  using  another library's OpenSSL compatibility interface, this may not work.  Since
              this variable only specifies a default value, the option --sslcertpath takes precedence if given.

       SSL_CERT_FILE
              (with truly OpenSSL 1.1.1 compatible library): overrides  OpenSSL's  idea  of  the  default  trust
              certificate  bundle  file  (which  contains  a concatenation of base64-encoded certificates in PEM
              format), see the SSL_CTX_set_default_verify_paths(3) manual page for details, it  may  be  in  the
              openssl development package.  If using another library's OpenSSL compatibility interface, this may
              not work.  Since this variable only specifies a default  value,  the  option  --sslcertfile  takes
              precedence if given.

SIGNALS

       If  a  fetchmail daemon is running as root, SIGUSR1 wakes it up from its sleep phase and forces a poll of
       all non-skipped servers. For compatibility reasons, SIGHUP can also be used  in  6.3.X  but  may  not  be
       available in future fetchmail versions.

       If  fetchmail  is  running  in  daemon mode as non-root, use SIGUSR1 to wake it (this is so SIGHUP due to
       logout can retain the default action of killing it).

       Running fetchmail in foreground while a background fetchmail is running will do  whichever  of  these  is
       appropriate to wake it up.

BUGS, LIMITATIONS, AND KNOWN PROBLEMS

       Please check the NEWS file that shipped with fetchmail for more known bugs than those listed here.

       Fetchmail  cannot  handle user names that contain blanks after a "@" character, for instance "demonstr@ti
       on". These are rather uncommon and only hurt when using UID-based --keep setups, so the 6.X.Y versions of
       fetchmail will not be fixed.

       Fetchmail cannot handle configurations where you have multiple accounts that use the same server name and
       the same login. Any user@server combination must be unique.

       The assumptions that the DNS and in particular the checkalias options make are not often sustainable. For
       instance, it has become uncommon for an MX server to be a POP3 or IMAP server at the same time. Therefore
       the MX lookups may go away in a future release.

       The mda and plugin options interact badly.  In order to collect error status from the MDA, fetchmail  has
       to change its normal signal handling so that dead plugin processes do not get reaped until the end of the
       poll cycle.  This can cause resource starvation if too many zombies accumulate.  So either do not deliver
       to a MDA using plugins or risk being overrun by an army of undead.

       The  --interface  option  does  not  support  IPv6  and it is doubtful if it ever will, since there is no
       portable way to query interface IPv6 addresses.

       The RFC822 address parser used in multidrop mode chokes on some @-addresses that  are  technically  legal
       but bizarre.  Strange uses of quoting and embedded comments are likely to confuse it.

       In a message with multiple envelope headers, only the last one processed will be visible to fetchmail.

       Use  of  some  of  these  protocols  requires that the program send unencrypted passwords over the TCP/IP
       connection to the mail server.  This creates a risk that name/password pairs might  be  snaffled  with  a
       packet  sniffer  or  more  sophisticated  monitoring  software.  Under Linux and FreeBSD, the --interface
       option can be used to restrict polling to availability of a specific interface  device  with  a  specific
       local  or  remote IP address, but snooping is still possible if (a) either host has a network device that
       can be opened in promiscuous mode, or (b) the intervening network link can be tapped.  We  recommend  the
       use of ssh(1) tunnelling to not only shroud your passwords but encrypt the entire conversation.

       Use  of  the  %F  or  %T  escapes  in  an  mda  option could open a security hole, because they pass text
       manipulable by an attacker to a shell command.  Potential shell characters are  replaced  by  '_'  before
       execution.   The  hole  is  further  reduced  by the fact that fetchmail temporarily discards any set-uid
       privileges it may have while running the MDA.  For maximum safety, however, do not  use  an  mda  command
       containing %F or %T when fetchmail is run from the root account itself.

       Fetchmail's  method of sending bounces due to errors or spam-blocking and spam bounces requires that port
       25 of localhost be available for sending mail via SMTP.

       If you modify ~/.fetchmailrc while a background instance is running and break the syntax, the  background
       instance  will  die  silently.   Unfortunately,  it cannot die noisily because we do not yet know whether
       syslog should be enabled.  On some systems, fetchmail dies quietly even if there is no syntax error; this
       seems to have something to do with buggy terminal ioctl code in the kernel.

       The -f - option (reading a configuration from stdin) is incompatible with the plugin option.

       The 'principal' option only handles Kerberos IV, not V.

       Interactively  entered  passwords  are  truncated after 63 characters. If you really need to use a longer
       password, you will have to use a configuration file.

       A backslash as the last character of a configuration file will be flagged as a syntax error  rather  than
       ignored.

       The BSMTP error handling is virtually nonexistent and may leave broken messages behind.

       Send  comments,  bug  reports,  gripes,  and  the  like  to  the  fetchmail-devel list ⟨mailto:fetchmail-
       devel@lists.sourceforge.net⟩

       An fetchmail FAQ (in HTML form) ⟨https://fetchmail.sourceforge.io/fetchmail-FAQ.html⟩ is available at the
       fetchmail home page, it should also accompany your installation.

AUTHOR

       Fetchmail is currently maintained by Matthias Andree and Rob Funk with major assistance from Sunil Shetye
       (for code) and Rob MacGregor (for the mailing lists).

       Most of the code is from Eric S. Raymond ⟨mailto:esr@snark.thyrsus.com⟩.  Too many other people  to  name
       here have contributed code and patches.

       This  program  is  descended  from  and replaces popclient, by Carl Harris ⟨mailto:ceharris@mal.com⟩; the
       internals have become quite different, but some of its interface design is  directly  traceable  to  that
       ancestral program.

       This manual page has been improved by Matthias Andree, R. Hannes Beinert, and Héctor García.

SEE ALSO

       README, README.SSL, README.SSL-SERVER, The Fetchmail FAQ ⟨https://www.fetchmail.info/fetchmail-FAQ.html⟩,
       mutt(1),  elm(1),  mail(1),  sendmail(8),  popd(8),  imapd(8),  netrc(5),   the   fetchmail   home   page
       ⟨https://www.fetchmail.info/⟩,  (alternative  URI) ⟨https://fetchmail.sourceforge.io/⟩; the maildrop home
       page.  ⟨https://www.courier-mta.org/maildrop/⟩

APPLICABLE STANDARDS

       Note that this list is just a collection of references and not a statement  as  to  the  actual  protocol
       conformance or requirements in fetchmail.

       SMTP/ESMTP:
            RFC 821, RFC 2821, RFC 1869, RFC 1652, RFC 1870, RFC 1983, RFC 1985, RFC 2554.

       mail:
            RFC 822, RFC 2822, RFC 1123, RFC 1892, RFC 1894.

       POP2:
            RFC 937

       POP3:
            RFC 1081, RFC 1225, RFC 1460, RFC 1725, RFC 1734, RFC 1939, RFC 1957, RFC 2195, RFC 2449.

       APOP:
            RFC 1939.

       RPOP:
            RFC 1081, RFC 1225.

       IMAP2/IMAP2BIS:
            RFC 1176, RFC 1732.

       IMAP4/IMAP4rev1:
            RFC 1730, RFC 1731, RFC 1732, RFC 2060, RFC 2061, RFC 2195, RFC 2177, RFC 2683.

       ETRN:
            RFC 1985.

       ODMR/ATRN:
            RFC 2645.

       OTP: RFC 1938.

       LMTP:
            RFC 2033.

       GSSAPI:
            RFC  1508, RFC 1734, Generic Security Service Application Program Interface (GSSAPI)/Kerberos/Simple
            Authentication and Security Layer  (SASL)  Service  Names  ⟨https://www.iana.org/assignments/gssapi-
            service-names/⟩.

       TLS: RFC 2595.