>>>>> "PZ" == Peter Zenge <email@example.com> writes:
PZ> What's the proper address for MTA's to use when a recipient does not
PZ> exist: From, Sender, or Reply-To (= the list)?
Neither. Bounces go to the envelope sender, which might not be directly
reflected in any header. This is generally owner-listname@host.
PZ> I'm running into several Lotus cc:mail gateways that insist on using
PZ> the Reply-To address, and causing loops.
Well, don't use reply-to. You've discovered one of the problems with it.
You cannot control all of the broken software out there.
PZ> Should majordomo be catching those, or is it up to me to stop the loop
PZ> and inform the other site's postmaster?
They're messages sent to the list just like any other. Majordomo can't
know a priori how to stop them. If they have some distinguishing
features, add something to taboo_headers or taboo_body to stop them, or
just get rid of reply-to.
Contacting the postmaster of the offending site is something that you
should always do when they screw up, but don't expect them to do anything.
If you want, just drop all of their users. It depends on your headache