[Mimedefang] Re: Forged Sender Checking

[Jeremy Mates]

* Lucas Albers <admin at cs.montana.edu>
> Seems to add 3-4 seconds on a mail delivery.
> So I greylist and then do a email_is_forged lookup.

And if your site does much traffic with the domains being forged,
manually exclude them from the reverse check if you can guess what the
legitimate outgoing hosts for the domain in question are. Something SPF
takes the guesswork out of...

> made some minor improvements to your code:
> adding logging if dns lookups fail.
> added timeout on dns lookups.

Where is the timeout being done? All I see is $timeout being set to 1,
and the documentation for Net::DNS uses that variable only with some
IO::Select code.

Updated my example code to log no MX being found, and to use A record in
such a case:

http://sial.org/howto/mimedefang/check-sender/