From: Bruno De Fraine (brunodefraine.net)
Date: Mon Sep 03 2007 - 08:40:08 CDT

• Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

Hello Postfix users,

I've got a filter command that I would like to use to tag all the
messages that pass through my mail server. The filter reads an entire
message on stdin, and outputs one line on stdout. This line should be
added as a header (e.g. "X-Filter-Result") to the message, which can
be delivered just as before. In case the filter exits with an error
(for whatever reason), the message can just pass-through untagged.

FILTER_README proposes two solutions: simple or advanced filters. The
simple filter is a sendmail-like command that receives the message
and that is responsible for reinjecting it in the mail queue with the
true sendmail command. This is close to what I have already, and I
could use a shell script and procmail's formail command to try to
bridge the gap. The downside seems to be that local messages cannot
be scanned as well (since Postfix needs to treat them as already
filtered to avoid a loop), and the documentation labels this method
as less reliable and slower (can you avoid this by programming the
simple filter in a different style or with a different programming
language?).

The advanced filter is a full SMTP proxy; it can overcome these
downsides but it is obviously a lot of effort to set-up, especially
since it should preferably support XFORWARD. The documentation refers
to a third party SMTP proxy which you can use, but, I have more faith
in Postfix's own SMTP implementation. Presumably, you cannot do this
without setting up a second Postfix instance? Besides, if this second
Postfix instance is just going to start the filter command, why would
it be any faster or more reliable than the simple filter?

Anyhow, any ideas on how to set up this filter are very welcome!

Thanks,
Bruno De Fraine

• Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]