Provided by: courier-mta_0.60.0-2ubuntu1_i386 bug


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


           $ cat $HOME/.courier
           || dotforward


       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 Courier.

       The different security models of Courier 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 Courier 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. Courier 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 Courier 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 Courier will proceed with additional delivery
       instructions in the .courier after finishing with the delivery
       instructions it reads from dotforward.


       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.




        1. dot-courier(5)