[Mimedefang] Powerful anti-spam rule :-)

[David F. Skoll]

Hi,

In the development of CanIt, I've discovered a really powerful
anti-spam rule:

For the following domains:

	aol.com
	earthlink.net
	hotmail.com
	yahoo.com

Reject mail unless the relay machine resolves to one whose name
ends in the same domain.

This kills a ton of spam, while only very occasionally dropping a
legit message -- most real users of those services relay via the
official mail servers, because they're too unsophisticated to do
otherwise.

This rule can go in filter_sender so you don't even start accepting
the message body.

Regards,

David.