@node Postfix
@cindex Postfix integration
@pindex postfix
@section Integration with Postfix

This section is taken from @url{http://www.postfix.org/UUCP_README.html,
Postfix and UUCP} manual and just replaces UUCP-related calls with NNCP
ones.

@strong{Setting up a Postfix Internet to NNCP gateway}

Here is how to set up a machine that sits on the Internet and that forwards
mail to a LAN that is connected via NNCP.

@itemize

@item You need an @ref{nncp-exec} program that extracts the sender
address from mail that arrives via NNCP, and that feeds the mail into
the Postfix @command{sendmail} command.

@item Define a @command{pipe(8)} based mail delivery transport for
delivery via NNCP:
@example
/usr/local/etc/postfix/master.cf:
nncp      unix  -       n       n       -       -       pipe
  flags=Rqhu user=nncp argv=nncp-exec -quiet $nexthop sendmail $recipient
@end example

This runs the @command{nncp-exec} command to place outgoing mail into
the NNCP queue after replacing @var{$nexthop} by the receiving NNCP
node and after replacing @var{$recipient} by the recipients. The
@command{pipe(8)} delivery agent executes the @command{nncp-exec}
command without assistance from the shell, so there are no problems with
shell meta characters in command-line parameters.

@pindex sendmail.sh
@vindex Return-Path
@pindex reformail
Pay attention to @code{flags}, containing @code{R}, telling Postfix to
include @code{Return-Path:} header. Otherwise that envelope sender
information may be lost. Possibly you will also need somehow to
preserve that header on the receiving side, because @command{sendmail}
command will replace it. For example you can rename it before feeding to
@command{sendmail} with
@code{reformail -R Return-Path: X-Original-Return-Path: | sendmail}, or
extract with:

@verbatiminclude sendmail.sh

@vindex From_
@cindex mbox
@pindex maildrop
Also pay attention that @command{maildrop} does not like @code{From_}
mbox-style header, so you possibly want:

@example
mailbox_command = reformail -f0 | maildrop -d $@{USER@}
@end example

@item Specify that mail for @emph{example.com}, should be delivered via
NNCP, to a host named @emph{nncp-host}:

@example
/usr/local/etc/postfix/transport:
    example.com     nncp:nncp-host
    .example.com    nncp:nncp-host
@end example

See the @command{transport(5)} manual page for more details.

@item Execute the command @command{postmap /etc/postfix/transport}
whenever you change the @file{transport} file.

@item Enable @file{transport} table lookups:

@example
/usr/local/etc/postfix/main.cf:
    transport_maps = hash:$config_directory/transport
@end example

@item Add @emph{example.com} to the list of domains that your site is
willing to relay mail for.

@example
/usr/local/etc/postfix/main.cf:
    relay_domains = example.com @dots{}other relay domains@dots{}
@end example

See the @option{relay_domains} configuration parameter description for
details.

@item Execute the command @command{postfix reload} to make the changes
effective.

@end itemize

@strong{Setting up a Postfix LAN to NNCP gateway}

Here is how to relay mail from a LAN via NNCP to the Internet.

@itemize

@item You need an @ref{nncp-exec} program that extracts the sender
address from mail that arrives via NNCP, and that feeds the mail into
the Postfix @command{sendmail} command.

@item Specify that all remote mail must be sent via the @command{nncp}
mail transport to your NNCP gateway host, say, @emph{nncp-gateway}:

@example
/usr/local/etc/postfix/main.cf:
    relayhost = nncp-gateway
    default_transport = nncp
@end example

Postfix 2.0 and later also allows the following more succinct form:

@example
/usr/local/etc/postfix/main.cf:
    default_transport = nncp:nncp-gateway
@end example

@item Define a @command{pipe(8)} based message delivery transport for
mail delivery via NNCP:

@example
/usr/local/etc/postfix/master.cf:
nncp      unix  -       n       n       -       -       pipe
  flags=Fqhu user=nncp argv=nncp-exec -quiet $nexthop sendmail $recipient
@end example

This runs the @command{nncp-exec} command to place outgoing mail into
the NNCP queue. It substitutes the hostname (@emph{nncp-gateway}, or
whatever you specified) and the recipients before execution of the
command. The @command{nncp-exec} command is executed without assistance
from the shell, so there are no problems with shell meta characters.

@item Execute the command @command{postfix reload} to make the changes
effective.

@end itemize