This is a very tricky situation. Whether or not I'd suggest you intervene
would depend on what you mean by "hate mail."
If the mail is threatening, harrassing, or illegal in any way, I would give
full cooperation. Ask to see a copy of it first.
If the mail is just plain mean and only happens once, I'd probably say,
work it out between yourselves (not that this is really possible with most
If the mail is just plain mean and happens many times, I'd put it in the
category of harressment and treat with full cooperation. The fact that it
is anon makes it more harressing, IMHO. An inbetween form of cooperation
is to simply say "yes" to the question of do you have a user with the
following domain. That way the reciever can at least complain to the
proper postmaster. If the postmaster then asks you directly for the
username, give it.
If you think the anon mail is sigificant enough to do something about but
don't feel comfortable giving your subscriber info to the reciever, you can
contact the postmaster directly. Send them a copy of the mail(s) in
question and ask them to look into it.
Do be sure in any case that you look up the domain to get the upstream
provider. If it's a virtual domain, sending to postmaster@domain will just
get the sender of the anon mail (unless of course that's what you want).
"There's nothing wrong with me. Maybe there's Cyndi Norman
something wrong with the universe." (ST:TNG) firstname.lastname@example.org