[...spam blowback...] the messages were of three types -- 554s
(unknown recipient or, more sadly, mailbox full), challenge-response
requests, and spam bounces. The latter two are the subject of my
post.
Challenge-Response requests: A company with the moniker
"spamarrest.com"
The people who held spamarrest.com at the time ran an anti-spam
"service" that, among other things, scraped its customers'
correspondents' addresses - and then spammed them with ads for
spamarrest. Unless the current holder of the domain is not the then
holder of it (and I'd need a lot of convincing), run, do not walk, to
the "block anything that smells even vaguely of this domain" portion of
your mailer configuration.
[...Barracudas...backscatter...] sadly, each appliance comes
configured by default to do "backscatter".
The _just_ thing to do seems to me to be to have your mailer
autocomplain to Barracuda, once per misdirected backscatter message
received. (Whether that would help in any way beyond making you feel
better is doubtful; I expect Barracuda would simply block you and
forget it.)
Autocomplaining to the generating site might do some good.
Beyond that, about all I can do is remark that when I ended up getting
hit with several thousand bounce blowback messages a few years back, I
made my mailer pick apart bounces and, if the bounced message didn't
bear certain traits that all my outgoing mail bears, reject the bounce.
(Sites that bounced in non-RFC3462 ways and didn't fix it I simply
blocked entirely.)
/~\ The ASCII der Mouse
\ / Ribbon Campaign
X Against HTML
mouse(_at_)rodents(_dot_)montreal(_dot_)qc(_dot_)ca
/ \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B
_______________________________________________
Asrg mailing list
Asrg(_at_)ietf(_dot_)org
https://www1.ietf.org/mailman/listinfo/asrg