I have a pretty decent setup going with sendmail, procmail, fetchmail, SpamAssassin, and ClamAV (to detect viruses before they get to my family's Window machines).

I'm pretty happy with the setup, but I'm getting increasingly annoyed with spam that contain nonsense paragraphs which seem to always get by SpamAssassin. One thing I've noticed with these spam is that they almost always have multiple recipients to people using the same ISP as I am. In other words, my address is "me@myisp.com" and the other recipients are "him@myisp.com", "her@myisp.com", "them@myisp.com". We share the same domain in our email addresses.

I'm pretty sure that there are procmail recipes where you can simply catch spam that have multiple recipients, but I don't want to do that, per se, because I do occasionally get legitimate emails with multiple recipients. However, these legitimate emails almost always have multiple recipients from different domains.

What procmail recipe could I use to catch multiple recipients that share the same domain as I do in email addresses? In other words, is there a way that procmail could detect more than, say, 3 recipients with "myisp.com" in their addresses?

It's late and I'm tired so I really hope I'm making sense here and I also hope I'm not asking a dumb question.

Thanks in advance,

LocoMojo