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dot-forward(1)

NAME

   dotforward, dot-forward - Read $HOME/.forward

SYNOPSIS

   $ cat $HOME/.courier
   || dotforward
   ./Maildir

DESCRIPTION

   The dotforward program is a compatibility module that reads forwarding
   instructions in $HOME/.forward.  dotforward is used for compatibility
   with sendmail or other mail servers that use the $HOME/.forward file.
   The dotforward program is intended to be executed from a
   dot-courier(5)[1] delivery instruction file. The system administrator
   can add it to the default set of delivery instructions, thus
   unilaterally implementing $HOME/.forward systemwide. To read forwarding
   instructions from $HOME/.forward, put "|| dotforward" on the first line
   of $HOME/.courier*. "|| dotforward" can also be added to the
   DEFAULTDELIVERY setting in the courierd configuration file. In both
   cases it must be followed by a newline, and the remaining delivery
   instructions, which will be used if $HOME/.forward does not exist.

   dotforward expects to be invoked from dot-courier(5)[1] delivery
   instruction file via the "||" operator (or from DEFAULTDELIVERY).
   dotforward checks its environment, reads the message from standard
   input, reconciles its environment with the contents of $HOME/.forward,
   then prints on standard output equivalent dot-courier(5)[1] compatible
   delivery instructions. The "||" operator reinterprets dotforward's
   output as additional delivery instructions, by the Courier mail server.

   The different security models of the Courier mail server and other mail
   servers that use $HOME/.forward, such as sendmail, means that it is not
   possible to faithfully duplicate 100% of the behavior of $HOME/.forward
   that originated with sendmail. The following section documents the
   behavior of the dotforward utility in the the Courier mail server mail
   server.

   $HOME/.forward processing
   dotforward reads the DTLINE environment variable, and the headers of
   the message being delivered, from standard input.  DTLINE contains the
   recipient's E-mail address. The Delivered-To headers list the
   recipients that already received this message. This is used to prevent
   mail loops between $HOME/.forward files from different recipients,
   which forward mail to each other.

   If $HOME/.forward does not exist, dotforward quietly terminates with a
   zero exit code, doing nothing. The remaining delivery instructions in
   $HOME/.courier are then carried out.

   If $HOME/.forward exists, it is expected to contain a list of addresses
   that the message should be forwarded to. An address may be an actual
   E-mail address, or a name of a program or a mailbox. Each line in
   $HOME/.forward should contain a list of comma-separated addresses. Use
   "| /path/to/program" (including the double quotes) to specify a
   delivery to a program (the message is piped to the given program). Use
   "/path/to/mailbox" or "./path/to/mailbox" (again including the double
   quotes) to specify a delivery to a mailbox (relative to $HOME in the
   second case).

   "| /path/to/program", "/path/to/mailbox", and "./path/to/mailbox" may
   also be listed on a line by themselves without the double quotes.

   All other addresses are interpreted as E-mail addresses where the mail
   should be forwarded. Any backslash at the beginning of an E-mail
   address is removed. Backslashes are used by sendmail to prevent mail
   loops. The Courier mail server does not need the backslashes -- it uses
   a different mechanism to prevent mail loops.

   Every E-mail address is checked against the list of E-mail addresses
   found in Delivered-To headers. If the E-mail address specified in
   $HOME/.forward matches any address in the Delivered-To header, it is
   automatically removed from a list of addresses.

   dotforward normally terminates with the exit code set to 99. This
   results in the Courier mail server considering the message to be
   succesfully delivered, and any additional delivery instructions in the
   .courier file will not be carried out. If an address read from
   $HOME/.forward matches the address in the DTLINE environment variable,
   the address is removed from the list of addresses that the message will
   be forwarded to, and dotforward terminates with the exit code set to 0
   (after printing all the relevant delivery instructions to standard
   output). The messages will be forwarded, and the Courier mail server
   will proceed with additional delivery instructions in the .courier
   after finishing with the delivery instructions it reads from
   dotforward.

BUGS

   The restrictions and precautions mentioned in dot-courier(5)[1] are
   also applicable here. There is an upper limit on the maximum number of
   characters that are read from any process executed by ||. Also if any
   delivery instruction fails with a transit exit code, the message will
   be completely redelivered at a later point, even to all the addresses
   it has been succesfully delivered the first time around.

AUTHOR

   Sam Varshavchik
       Author

NOTES

    1. dot-courier(5)
       [set $man.base.url.for.relative.links]/dot-courier.html

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