Piping messages from MailScanner

[Justin]

Short version: Can messages be "piped" from MailScanner to another process,
as opposed to writing messages to a spool file?

Long version:

We're trying to figure out the best way to achieve the following general
flow:

1. Mail is checked for viruses and run through spam filters via MailScanner
2. If spam score is below a certain threshold, deliver.
   If the score is above a certain threshold, quarantine/discard.
   If SA can't confidently classify as spam or ham, challenge via TMDA

We'll call step #2 above the "Challenge Check." We're trying to figure out
which process should be handling the Challenge Check logic outlined above.
The XAMS configuration currently looks like this:

1. Mail received by Exim is stored in /var/spool/exim-incoming
2. MailScanner (MS) reads exim-incoming spool & checks for new messages
3. MS processes messages (virus checking, SpamAssassin, etc.)
4. MS writes cleaned & tagged messages to /var/spool/exim-outgoing
5. Exim-outgoing process delivers any mail it finds in exim-outgoing spool

(See following link for more detail:)

http://www.xams.org/documentation/xams-mailscanner.pdf

The question is: where is the best place for the Challenge Check to go?
Should MailScanner handle this logic? SpamAssassin? TMDA?

TMDA can handle this logic, provided there is a way for us to "pipe"
messages from MailScanner to TMDA. Is there a way to do this?

Exim can pipe messages to TMDA via a transport, but of course we would like
to have the messages treated by MailScanner first -- hence the question.

Any suggestions?

Thanks a bunch,

Justin

Member, XAMS Project Team
http://www.xams.org/
XAMS: Smarter email management