Looking at options here for eliminating backscatter. I've reviewed the Howto for this, but it only seems to be effective against backscatter where one's home domain is forged - not too useful, IMNSHO, because spammers aren't always going to forge the home domain.
One thing I've been looking at doing is basically checking headers, and if the From: header is null, then reject it immediately. Other approach is to eliminate my 2ary MX from DNS - most of my spam comes from that. I don't really want to do that, though, because the idea of a 2ary MX is for a fallback. Thoughts? -Dennis