Backscatter is the new spam. Spammers are intentionally sending spam that will be returned in the bounce message. We have configured our MTA to not bounce messages to invalid addresses on our server (in violation of RFC 822) to cut down on this spam source. But listserv is now a major source of backscatter spam.

The backscatter problem has become overwhelming, and has gotten our site blacklisted by AT&T and MSN. Spam messages from non-subscribed addresses are sent to the list, and listserv dutifully sends a "you are not authorized.." reply. We see about 300 of these an hour. While it violates the RFCs, AT&T and MSN have told us we need to not reply to these bogus posts (which contain typical spam messages). Is there a way to configure listserv v 14 to ignore posts from non-subscribers, rather than to send reject messages?

We have a similar problem with bogus SUBSCRIBE messages. We get about 300 of these per day. Each one results in a confirmation message being sent to the bogus address in the subscribe request. These are treated as spam by AT&T and MSN. We're afraid to turn off CONFIRM for obvious reasons.