>We have proper A+PTR records on the edge MTAs, proper SPF records for >the originating domain, proper Return-Path and other headers, and so >on. There isn't anything that I can think of other than the content >itself which would be abnormal, and obviously the content is >repetitive and can't be changed much. Is there something obvious >which we've missed?
What else goes out from that MTA? User forwarded mail? Mailing lists? random customer junk? It is a really good idea to separate your mail streams. These days it means separate IPs for users, transactions, forwards, and such, eventually different DKIM signatures will do the trick. R's, John
