Hello,
Postfix allows a content filter to be configured as part of the message
sending chain (via the content_filter parameter), and the content filter
can be a script which is invoked using the pipe delivery agent. Looking
at the pipe.c source code, it looks like the eval_command_status
function will always bounce or defer e-mail unless command_status is
PIPE_STAT_OK, in which case Postfix will log 2.0.0 (mail delivered via...)
The trouble is, a content filter may want to discard the e-mail (for
instance, if it is sure it's spam), yet not generate a bounce. At the
moment, it looks like the only way to do this is to drop the message,
then lie to Postfix and return 0, causing Postfix to log the e-mail as
delivered. There is no way to tell Postfix "the e-mail wasn't
delivered, but don't generate a bounceback".
Looking at RFC 3463 (http://tools.ietf.org/html/rfc3463) I think an
appropriate error code for when an e-mail is rejected because it's spam
(and therefore you likely don't want to generate a bounceback) would be
5.6.0:
Other or undefined media error
Something about the content of a message caused it to be
considered undeliverable and the problem cannot be well
expressed with any of the other provided detail codes.
So how about modifying the pipe delivery agent so that when the called
script returns EX_DATAERR (65, which maps to 5.6.0 in sys_exits.c),
Postfix by default does not generate a bounceback, but have a
configuration option that can be set to turn bounces on again for
EX_DATAERR?
--
Best regards,
Jeremy Morton (Jez)
