Provided by: vrfy_990522-6_amd64 bug

NAME

       vrfy - Verify electronic mail addresses

SYNTAX

       vrfy [options] [-v] address [host]
       vrfy [options] [-v] -f [file] [host]
       vrfy [options] [-v] -p domain
       vrfy [options] [-v] -T domain [name]

DESCRIPTION

       vrfy  is  a  tool to verify electronic mail addresses.  The only required parameter is the
       address to be verified.  The actual verification will be carried out at the remote machine
       where  mail to the given address would normally be delivered.  This may be a mail exchange
       host and not the final destination host.  If an explicit  host  is  given  as  the  second
       argument on the command line, the specified address is verified at that machine.

       The output of the program shows whether or not the address can be handled at the contacted
       host. Error messages will be printed  if  the  address  is  invalid.  If  the  address  is
       recognized,  the  output  shows  the  remote  host's  notion  of the (possibly translated)
       address. If it represents a local user at that host, additional information about the user
       may be displayed.

       Note  that  if  the  address  is accepted by the contacted host, but this is not the final
       destination host, one still cannot be sure that the address represents a valid recipient.

       It is a handy tool to verify local mail addresses.
       If you have set up a .forward file, you can verify your own  address  to  check  that  the
       forwarding is done properly.
       If  you  specify  an  arbitrary  name,  you  can  check whether this resolves to any valid
       recipients.

SPECIAL OPERATION MODES

       Some flags put the program in a special operation mode.

   FILE MODE
       If the -f option is specified, the program enters a  special  file  mode.  The  (optional)
       parameter  is  the  name  of a file containing electronic mail addresses, such as used for
       mailing lists.  Verification of all addresses present in the file  is  attempted.   If  no
       filename  is  specified,  vrfy  acts as a filter and the addresses to be verified are read
       from standard input.

   PING MODE
       If the -p option is specified, the program  enters  a  special  ping  mode.  The  required
       parameter  is  an  electronic  mail  domain  for  which  it  will  be verified whether the
       corresponding mail exchangers are currently responding to SMTP requests.

   ETRN MODE
       If the -T option is specified, the program  enters  a  special  etrn  mode.  The  required
       parameter  is  an  electronic mail domain.  An ESMTP ETRN command will be delivered to its
       corresponding mail exchangers. An optional name is used as the  ETRN  parameter.   If  not
       specified,  the  local  host  name  is  used instead.  ETRN is defined in RFC 1985, and is
       implemented in sendmail 8.8.

   RECURSIVE MODE
       If the -L level option is specified, the received replies to an address  verification  are
       recursively  verified  up  to  level  levels deep. This is handy for checking mailing list
       expansions, and detecting possible mail forwarding loops.

       Recursion stops automatically if the reply represents a local  recipient  address,  or  in
       case  a  forwarding loop is detected.  If the received reply is the same (modulo comments)
       as the address that was asked for, the request is retried at  its  domain  itself,  unless
       this was the machine we just queried, or it is not an internet domain host.

       The  option  -R  is  equivalent to ``-L 17''.  This is the maximum hop count normally used
       during actual mail relaying. This option also implies ``-s''.

OPTIONS

       -v      Sets verbose mode. Prints the action the program is going to take.
               If specified as -vv, very verbose output is printed.  The SMTP  transactions  with
               the remote host are shown in detail.
               If  the  verbose mode level is set to 3 with -vvv, the actions taken by the remote
               host are shown, such as alias and forward expansions. This can be  quite  amusing.
               The remote host must support the SMTP VERB command for this to work.
               In ping mode, the verbose mode level 3 will cause an extra SMTP command HELO to be
               generated.

       -d      Prints debugging output showing the various phases of the SMTP connection with the
               remote  host.  This  is normally not of any interest. Also prints various messages
               that are otherwise shown in very verbose mode.
               If specified as -dd, in addition all nameserver query transactions  are  shown  in
               detail.
               A level 3 debug mode -ddd will not make any SMTP connections at all.

       -a      If  multiple  mail exchange hosts were found, this option will cause the operation
               to be carried out at  each  of  these  hosts.   Normally  only  the  primary  mail
               exchanger is contacted.

       -l      Sets  local mode for error handling. Address syntax and parsing errors are handled
               entirely by the program. The default is to pass faulty addresses to the local host
               to get the official error messages.

       -s      Strips  all comments from full address specifications, and presents only the plain
               address to the remote host to be verified.  Some hosts may  get  confused  when  a
               multiple bracketed address is presented. This option is implied when -R is given.

       -e      Uses the EXPN command instead of the VRFY command. Some systems may have different
               treatment for these commands, so this option may be a  possible  alternative.   By
               sendmail  V5  they  are  usually  treated  the  same,  but  not by the sendmail V8
               versions.  In case treatment is different, the VRFY command will just show whether
               the  presented  address  is  valid  or not, but the EXPN command will return alias
               expansions, if appropriate.  Some  systems  allow  VRFY,  but  disallow  EXPN  for
               privacy reasons.

       -h      This  option  causes  an  SMTP  HELO  command to be issued to the contacted server
               before subsequent commands are attempted.  Servers can  be  configured  to  refuse
               commands unless a HELO command is given first.  The HELO is not issued by default,
               since old versions of sendmail refuse SMTP connections  originating  on  the  same
               machine (i.e. if the domain name in the HELO command is its own name).

       -H      Similar  to  the  -h option, but now the ESMTP EHLO command is tried first. If the
               contacted server does not understand this, the SMTP HELO command is tried next.

       -n      Many non-sendmail hosts do not, or incorrectly or incompletely, implement the VRFY
               command. Other systems have VRFY or EXPN disabled for privacy reasons. This option
               uses an alternative protocol suite with the regular  HELO,  MAIL,  RCPT  and  RSET
               commands.   This  gives  only  a global indication whether the recipient is valid.
               Recursive mode is not possible, and will be disabled.

       -S sender
               Defines an explicit envelope sender address to be used in the MAIL command  during
               the  alternative  protocol  suite,  to  overrule  the default empty sender address
               ``<>''.  This option implies ``-n''.

       -c secs Sets a connect timeout value to override the default timeout of  6  seconds.  This
               may be necessary if it takes considerable time to connect to the remote host.

       -t secs Sets  a read timeout value to override the default timeout of 60 seconds. This may
               be necessary if it takes considerable time for the remote  host  to  assemble  all
               addresses in long mailing lists.

DEFAULT OPTIONS

       Default  options  and  parameters  can  be preset in an environment variable VRFY_DEFAULTS
       using the same syntax as on the command line. They will be evaluated  before  the  command
       line arguments.

DIAGNOSTICS

       vrfy  sets up an SMTP connection with the remote host where the verifying is to be carried
       out.  SMTP is the TCP/IP protocol for electronic mail exchange.

       If the given host does not speak SMTP, the error message "Connection refused" is printed.

       If the SMTP protocol is blocked, a "Host is unreachable" message is printed.

       If the remote host doesn't respond in time, you will get a "Connection timed out" message.

       The remote host must support the SMTP VRFY command for doing the verification. If  not,  a
       "Command not implemented" is printed.

STRATEGY

       The  following  strategy  is  used to find the remote host where the verification is to be
       carried out.

       a.  If an explicit verification host is specified, that host is contacted unconditionally.

       b.  If the address to be verified has no domain part after an '@' sign, it is supposed  to
           be a local recipient and will be verified at the local host.

       c.  If  the  address contains a domain part after an '@' sign, mail exchange hosts will be
           fetched for that domain. If no such mail exchangers are  found,  the  domain  part  is
           supposed to represent a specific host, and that host itself will be contacted.

       d.  If  mail  exchangers  were  found, the verification will be carried out at the primary
           mail exchange host.

       e.  If the -a option was given, and multiple mail exchangers exist,  the  verification  is
           also carried out at all other mail exchange hosts.

       f.  For the pseudo domains ".uucp" and ".bitnet" a specific server can be compiled-in. The
           default is to contact the local host.

       g.  If no mail exchangers were found for an unqualified single hostname, the local host is
           contacted  by  default.  The  actual  meaning  of  such addresses depend on your local
           strategy.

ENVIRONMENT

       Environment variables can be used to overrule several compiled-in defaults.

   VRFY_LOCALHOST
       This is your nearest host running the sendmail daemon.  It  is  contacted  in  case  local
       addresses  without  a domain are given.  Also (unless the -l is given) when domain parsing
       errors were encountered, assuming that  this  host  can  give  a  more  appropriate  error
       message.  The default value is localhost.

   VRFY_UUCPRELAY
       This  host  is  contacted  when a .uucp address is specified.  You probably won't get much
       useful information.  The default value is localhost.

   VRFY_BITNETRELAY
       This host is contacted when a .bitnet or .earn address is specified.  You  probably  won't
       get much useful information.  The default value is localhost.

   VRFY_SINGLERELAY
       This  host  is  contacted  when  a single unqualified host name could not be resolved to a
       fully qualified MX domain host.  It is assumed that single hosts in your own domain can be
       resolved,  i.e. they have an MX record.  It depends on your local strategy for unqualified
       hosts what they mean: a .uucp host, a .bitnet host, or just a local host without MX.   The
       default value is localhost.

LIMITATIONS

       Some  hosts  have  a lousy VRFY handling. Sometimes the command is not implemented at all.
       Other hosts are willing to verify only local recipients. The "-n" option may be necessary.

       Other servers may refuse the VRFY command for privacy reasons.

       If the verification is not performed at the final destination host,  one  cannot  be  sure
       that the given address is valid.

MAILING LISTS

       Note  the following subtle differences if you want to check an existing mailing list list.
       Suppose  that  ``list-users''  is  the  local   alias   to   include   the   actual   file
       ``/mail/lists/list-users'' with recipients.

       The  command  ``vrfy list-users''  will verify the proper expansion of the mailing list at
       the local host. No remote hosts are contacted to verify addresses.

       The command ``vrfy -f /mail/lists/list-users'' will verify each individual address at  the
       appropriate remote hosts.

       The  same  effect can be reached when you give the command ``vrfy -L 1 list-users''. Use a
       higher recursion level if you want to see further expansion of the mailing list.

AUTHOR

       Eric Wassenaar, Nikhef-H, <e07@nikhef.nl>

                                              971114                                      vrfy(1)