At 10:56 AM -0500 1/6/03, Don Doumakes is rumored to have typed:
Recently I had an episode in which subscriber A started selectively bouncing all mail from subscriber B.
It's unlikely he's "bouncing" mail through his SMTP server; I could, for example, add your address to sendmail's access file as a REJECT, but your list messages would still get through, since when the list distributes a message _it_ is the envelope sender, not you. Looks more like A is doing something with procmail, or worse some moronic Windoze application that trusts the From: header field.
Leaving aside the question of why A and B can't just get along, is there a solution to the erroneous behavior? Is this a bug of which the developers are aware?
Since I can't see the bounces A was generating, I wouldn't want to declare that there _isn't_ some obscure bug in SmartList, but I'd be more prone to think the problem was the way A was bouncing the messages. I've (rarely) seen SmartList get confused by badly malformed mailer messages, but in 99.99% of the cases SmartList gets it right even then...and I've seen some so screwed up that _I_ had a hard time figuring out what address the mailer was rejecting.
Your specific problem doesn't seem to call for a technical solution, but rather a social one. My solution would be, as listmaster, to reinstate B and immediately unsubscribe A until A bought a clue on how to tell the difference between Return-Path: and From:. A is welcomed to dump mail from B to /dev/null, but A is _not_ welcomed to impact my mailing list server in a tiff with B. You don't need to judge (nor even _care_) who's "right" between A and B, you only need to show that B's actions are NOT impacting your server negatively, where A's ARE, so A needs the attitude adjustment.
Assuming A understood that sending mail back to the list was unacceptable and stopped it, I'd reinstate A provisionally (probably logging any mail from A's end of the world for a while to prevent it from happening again). If on the other hand A refused to deal with the problem, you're likely better off without A on your list anyway, since this _will_ happen again when A gets miffed at C. And D. And...
But that's just me, and you're welcomed to handle it however you feel comfortable. This would be an interesting question to pose to list-managers or the like, but I don't see SmartList being directly at fault here. This seems squarely within the social domain of the listmaster.
Charlie