[Mimedefang] Bad MX records, and how to handle them.

[David F. Skoll]

On Thu, 26 Jun 2003, Rick Robino wrote:

> My point is:  can someone hand my lazy self a
> filter rule that does an SMTP check to the MX list of wherever MD would
> normally send a bounce (or quarantine msg) to, that if there is no
> valid SMTP reply at all the message could be marked and then treated
> normally, allowing me to trash it or apply other rules?

This is very, very dangerous.  I believe a much safer option is to
periodically move bounce messages out of the regular queue into
a special queue that has a queue runner that runs less frequently
and has a shorter timeout.

Sendmail comes with a contributed script called "qtool" that can do
this.

Running something like this every so often from cron:

qtool.pl -e '$msg{num_delivery_attempts} >= 3 && $msg{sender} eq "<>"' \
	/var/spool/slow-mqueue /var/spool/mqueue

moves all messages that have been tried at least three times, and are from
"<>"  (indicating a bounce message) into /var/spool/slow-mqueue.
You can then have a separate, infrequent queue runner on slow-mqueue and
give it a shorter timeout.

--
David.