Dealing With SPAM Backscatter

In the last week or so, I’ve started to get a fair number (20 a day, at least) of spam backscatter undeliverable notices that get through my two spam filters (DH’s SpamAssassin and OS X’s Mail’s filter).

I know there isn’t a ton I can do about this, can anyone suggest some good filtering rules I could put in to be able to filter these out without having to worry about legitimate bounces being tossed without me catching them?

I’ve been looking at the headers but I’m having a tough time figuring out a rule that wouldn’t catch a ton of legitimate mail.

– Michael Cook

If you as a human can’t figure out a common element, then there’s not much hope of a filter doing a better job. When I get backscatter, it’s usually short-lived.