Larry wrote on 11/01/2008 03:19:57 PM:

> 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.

Those dirt-bag spammers!  How dare they?

> 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?

I have found the best option for dealing with unwanted messages is to
refuse the accept them at the SMTP level.  Many spam filters accept the
message and close the connection before evaluating the message.  If the
message is determined to be spam, what do you do with it.  Some filters
(ie. Barracuda, with default settings) send an email back to the alleged
sender also causing back scatter.  Most send an email to the recipient
listing the spam being held for them and most users ignore this message
too.

By refusing to accept the message, you put the onus on the delivering
server to return the message, or if the connecting system is a bot/zombie,
it may just disappear without bothering anyone.

Depending on your environment, you may already have a spam filter in lace
and it is easier to place Listserv behind it, rather than trying to manage
its spam filtering separately.

--
May you solve interesting problems

William Brown
Web Development & Messaging Services
Technology Services, WNYRIC, Erie 1 BOCES