Ubuntu Manpage: sendmail - an electronic mail transport agent

Provided by: sendmail-bin_8.15.2-3_amd64

NAME

       sendmail - an electronic mail transport agent

SYNOPSIS

       sendmail [flags] [address ...]
       newaliases
       mailq [-v]
       hoststat
       purgestat
       smtpd

DESCRIPTION

Sendmail sends a message to one or more recipients, routing the message over whatever
networks are necessary. Sendmail does internetwork forwarding as necessary to deliver the
message to the correct place.

Sendmail is not intended as a user interface routine; other programs provide user-friendly
front ends; sendmail is used only to deliver pre-formatted messages.

With no flags, sendmail reads its standard input up to an end-of-file or a line consisting
only of a single dot and sends a copy of the message found there to all of the addresses
listed. It determines the network(s) to use based on the syntax and contents of the
addresses.

Local addresses are looked up in a file and aliased appropriately. Aliasing can be
prevented by preceding the address with a backslash. Beginning with 8.10, the sender is
included in any alias expansions, e.g., if `john' sends to `group', and `group' includes
`john' in the expansion, then the letter will also be delivered to `john'.

Parameters
-Ac Use submit.cf even if the operation mode does not indicate an initial mail
submission.

-Am Use sendmail.cf even if the operation mode indicates an initial mail submission.

-Btype Set the body type to type. Current legal values are 7BIT or 8BITMIME.

-ba Go into ARPANET mode. All input lines must end with a CR-LF, and all messages will
be generated with a CR-LF at the end. Also, the ``From:'' and ``Sender:'' fields
are examined for the name of the sender.

-bC Check the configuration file.

-bd Run as a daemon. Sendmail will fork and run in background listening on socket 25
for incoming SMTP connections. This is normally run from /etc/rc.

-bD Same as -bd except runs in foreground.

-bh Print the persistent host status database.

-bH Purge expired entries from the persistent host status database.

-bi Initialize the alias database.

-bm Deliver mail in the usual way (default).

-bp Print a listing of the queue(s).

-bP Print number of entries in the queue(s); only available with shared memory support.

-bs Use the SMTP protocol as described in RFC821 on standard input and output. This
flag implies all the operations of the -ba flag that are compatible with SMTP.

-bt Run in address test mode. This mode reads addresses and shows the steps in
parsing; it is used for debugging configuration tables.

-bv Verify names only - do not try to collect or deliver a message. Verify mode is
normally used for validating users or mailing lists.

-Cfile Use alternate configuration file. Sendmail gives up any enhanced (set-user-ID or
set-group-ID) privileges if an alternate configuration file is specified.

-D logfile
Send debugging output to the indicated log file instead of stdout.

-dcategory.level...
Set the debugging flag for category to level. Category is either an integer or a
name specifying the topic, and level an integer specifying the level of debugging
output desired. Higher levels generally mean more output. More than one flag can
be specified by separating them with commas. A list of numeric debugging
categories can be found in the TRACEFLAGS file in the sendmail source distribution.
The option -d0.1 prints the version of sendmail and the options it was compiled
with.
Most other categories are only useful with, and documented in, sendmail's source
code.

-Ffullname
Set the full name of the sender.

-fname Sets the name of the ``from'' person (i.e., the envelope sender of the mail). This
address may also be used in the From: header if that header is missing during
initial submission. The envelope sender address is used as the recipient for
delivery status notifications and may also appear in a Return-Path: header. -f
should only be used by ``trusted'' users (normally root, daemon, and network) or if
the person you are trying to become is the same as the person you are. Otherwise,
an X-Authentication-Warning header will be added to the message.

-G Relay (gateway) submission of a message, e.g., when rmail calls sendmail .

-hN Set the hop count to N. The hop count is incremented every time the mail is
processed. When it reaches a limit, the mail is returned with an error message,
the victim of an aliasing loop. If not specified, ``Received:'' lines in the
message are counted.

-i Do not strip a leading dot from lines in incoming messages, and do not treat a dot
on a line by itself as the end of an incoming message. This should be set if you
are reading data from a file.

-L tag Set the identifier used in syslog messages to the supplied tag.

-N dsn Set delivery status notification conditions to dsn, which can be `never' for no
notifications or a comma separated list of the values `failure' to be notified if
delivery failed, `delay' to be notified if delivery is delayed, and `success' to be
notified when the message is successfully delivered.

-n Don't do aliasing.

-O option=value
Set option option to the specified value. This form uses long names. See below
for more details.

-ox value
Set option x to the specified value. This form uses single character names only.
The short names are not described in this manual page; see the Sendmail
Installation and Operation Guide for details.

-pprotocol
Set the name of the protocol used to receive the message. This can be a simple
protocol name such as ``UUCP'' or a protocol and hostname, such as ``UUCP:ucbvax''.

-q[time]
Process saved messages in the queue at given intervals. If time is omitted,
process the queue once. Time is given as a tagged number, with `s' being seconds,
`m' being minutes (default), `h' being hours, `d' being days, and `w' being weeks.
For example, `-q1h30m' or `-q90m' would both set the timeout to one hour thirty
minutes. By default, sendmail will run in the background. This option can be used
safely with -bd.

-qp[time]
Similar to -qtime, except that instead of periodically forking a child to process
the queue, sendmail forks a single persistent child for each queue that alternates
between processing the queue and sleeping. The sleep time is given as the
argument; it defaults to 1 second. The process will always sleep at least 5
seconds if the queue was empty in the previous queue run.

-qf Process saved messages in the queue once and do not fork(), but run in the
foreground.

-qGname
Process jobs in queue group called name only.

-q[!]Isubstr
Limit processed jobs to those containing substr as a substring of the queue id or
not when ! is specified.

-q[!]Qsubstr
Limit processed jobs to quarantined jobs containing substr as a substring of the
quarantine reason or not when ! is specified.

-q[!]Rsubstr
Limit processed jobs to those containing substr as a substring of one of the
recipients or not when ! is specified.

-q[!]Ssubstr
Limit processed jobs to those containing substr as a substring of the sender or not
when ! is specified.

-Q[reason]
Quarantine a normal queue items with the given reason or unquarantine quarantined
queue items if no reason is given. This should only be used with some sort of item
matching using as described above.

-R return
Set the amount of the message to be returned if the message bounces. The return
parameter can be `full' to return the entire message or `hdrs' to return only the
headers. In the latter case also local bounces return only the headers.

-rname An alternate and obsolete form of the -f flag.

-t Read message for recipients. To:, Cc:, and Bcc: lines will be scanned for
recipient addresses. The Bcc: line will be deleted before transmission.

-V envid
Set the original envelope id. This is propagated across SMTP to servers that
support DSNs and is returned in DSN-compliant error messages.

-v Go into verbose mode. Alias expansions will be announced, etc.

-X logfile
Log all traffic in and out of mailers in the indicated log file. This should only
be used as a last resort for debugging mailer bugs. It will log a lot of data very
quickly.

-- Stop processing command flags and use the rest of the arguments as addresses.

Options
There are also a number of processing options that may be set. Normally these will only
be used by a system administrator. Options may be set either on the command line using
the -o flag (for short names), the -O flag (for long names), or in the configuration file.
This is a partial list limited to those options that are likely to be useful on the
command line and only shows the long names; for a complete list (and details), consult the
Sendmail Installation and Operation Guide. The options are:

AliasFile=file
Use alternate alias file.

HoldExpensive
On mailers that are considered ``expensive'' to connect to, don't initiate
immediate connection. This requires queueing.

CheckpointInterval=N
Checkpoint the queue file after every N successful deliveries (default 10). This
avoids excessive duplicate deliveries when sending to long mailing lists
interrupted by system crashes.

DeliveryMode=x
Set the delivery mode to x. Delivery modes are `i' for interactive (synchronous)
delivery, `b' for background (asynchronous) delivery, `q' for queue only - i.e.,
actual delivery is done the next time the queue is run, and `d' for deferred - the
same as `q' except that database lookups for maps which have set the -D option
(default for the host map) are avoided.

ErrorMode=x
Set error processing to mode x. Valid modes are `m' to mail back the error
message, `w' to ``write'' back the error message (or mail it back if the sender is
not logged in), `p' to print the errors on the terminal (default), `q' to throw
away error messages (only exit status is returned), and `e' to do special
processing for the BerkNet. If the text of the message is not mailed back by modes
`m' or `w' and if the sender is local to this machine, a copy of the message is
appended to the file dead.letter in the sender's home directory.

SaveFromLine
Save UNIX-style From lines at the front of messages.

MaxHopCount=N
The maximum number of times a message is allowed to ``hop'' before we decide it is
in a loop.

IgnoreDots
Do not take dots on a line by themselves as a message terminator.

SendMimeErrors
Send error messages in MIME format. If not set, the DSN (Delivery Status
Notification) SMTP extension is disabled.

ConnectionCacheTimeout=timeout
Set connection cache timeout.

ConnectionCacheSize=N
Set connection cache size.

LogLevel=n
The log level.

MeToo=False
Don't send to ``me'' (the sender) if I am in an alias expansion.

CheckAliases
Validate the right hand side of aliases during a newaliases(1) command.

OldStyleHeaders
If set, this message may have old style headers. If not set, this message is
guaranteed to have new style headers (i.e., commas instead of spaces between
addresses). If set, an adaptive algorithm is used that will correctly determine
the header format in most cases.

QueueDirectory=queuedir
Select the directory in which to queue messages.

StatusFile=file
Save statistics in the named file.

Timeout.queuereturn=time
Set the timeout on undelivered messages in the queue to the specified time. After
delivery has failed (e.g., because of a host being down) for this amount of time,
failed messages will be returned to the sender. The default is five days.

UserDatabaseSpec=userdatabase
If set, a user database is consulted to get forwarding information. You can
consider this an adjunct to the aliasing mechanism, except that the database is
intended to be distributed; aliases are local to a particular host. This may not
be available if your sendmail does not have the USERDB option compiled in.

ForkEachJob
Fork each job during queue runs. May be convenient on memory-poor machines.

SevenBitInput
Strip incoming messages to seven bits.

EightBitMode=mode
Set the handling of eight bit input to seven bit destinations to mode: m (mimefy)
will convert to seven-bit MIME format, p (pass) will pass it as eight bits (but
violates protocols), and s (strict) will bounce the message.

MinQueueAge=timeout
Sets how long a job must ferment in the queue between attempts to send it.

DefaultCharSet=charset
Sets the default character set used to label 8-bit data that is not otherwise
labelled.

DialDelay=sleeptime
If opening a connection fails, sleep for sleeptime seconds and try again. Useful
on dial-on-demand sites.

NoRecipientAction=action
Set the behaviour when there are no recipient headers (To:, Cc: or Bcc:) in the
message to action: none leaves the message unchanged, add-to adds a To: header with
the envelope recipients, add-apparently-to adds an Apparently-To: header with the
envelope recipients, add-bcc adds an empty Bcc: header, and add-to-undisclosed adds
a header reading `To: undisclosed-recipients:;'.

MaxDaemonChildren=N
Sets the maximum number of children that an incoming SMTP daemon will be allowed to
spawn at any time to N.

ConnectionRateThrottle=N
Sets the maximum number of connections per second to the SMTP port to N.

In aliases, the first character of a name may be a vertical bar to cause interpretation of
the rest of the name as a command to pipe the mail to. It may be necessary to quote the
name to keep sendmail from suppressing the blanks from between arguments. For example, a
common alias is:

msgs: "|/usr/bin/msgs -s"

Aliases may also have the syntax ``:include:filename'' to ask sendmail to read the named
file for a list of recipients. For example, an alias such as:

poets: ":include:/usr/local/lib/poets.list"

would read /usr/local/lib/poets.list for the list of addresses making up the group.

Sendmail returns an exit status describing what it did. The codes are defined in
<sysexits.h>:

EX_OK Successful completion on all addresses.

EX_NOUSER
User name not recognized.

EX_UNAVAILABLE
Catchall meaning necessary resources were not available.

EX_SYNTAX
Syntax error in address.

EX_SOFTWARE
Internal software error, including bad arguments.

EX_OSERR
Temporary operating system error, such as ``cannot fork''.

EX_NOHOST
Host name not recognized.

EX_TEMPFAIL
Message could not be sent immediately, but was queued.

If invoked as newaliases, sendmail will rebuild the alias database. If invoked as mailq,
sendmail will print the contents of the mail queue. If invoked as hoststat, sendmail will
print the persistent host status database. If invoked as purgestat, sendmail will purge
expired entries from the persistent host status database. If invoked as smtpd, sendmail
will act as a daemon, as if the -bd option were specified.

NOTES

       sendmail often gets blamed for many  problems  that  are  actually  the  result  of  other
       problems,  such  as  overly  permissive  modes  on directories.  For this reason, sendmail
       checks the modes on system directories and files to determine  if  they  can  be  trusted.
       Although  these  checks  can be turned off and your system security reduced by setting the
       DontBlameSendmail option, the permission problems should be fixed.  For more  information,
       see:

       http://www.sendmail.org/tips/DontBlameSendmail.html

FILES

       Except for the file /etc/mail/sendmail.cf itself the following pathnames are all specified
       in /etc/mail/sendmail.cf.  Thus, these values are only approximations.

        /etc/mail/aliases
              raw data for alias names

        /etc/mail/aliases.db
              data base of alias names

        /etc/mail/sendmail.cf
              configuration file

        /etc/mail/helpfile
              help file

        /var/lib/sendmail/sendmail.st
              collected statistics

        /var/spool/mqueue/*
              temp files

HISTORY