Just a quick note wrt replying to parent-domains of spam-
originators... Note that "domain.com" is just the example domain, and is
the default "reply-to" address for many mailers. If the reply-to
address is "user@domain.com" or "user@host.domain.com," YOU DON'T NEED
TO SEND ME MAIL TO TELL ME ABOUT IT, since thousands of other people
already do. 
Look at the sender address, not the reply-to address.
-Bill
Bill Woodcock writes:
> Just a quick note wrt replying to parent-domains of spam-
> originators... Note that "domain.com" is just the example domain, and is
> the default "reply-to" address for many mailers. If the reply-to
> address is "user@domain.com" or "user@host.domain.com," YOU DON'T NEED
> TO SEND ME MAIL TO TELL ME ABOUT IT, since thousands of other people
> already do. Look at the sender address, not the reply-to address.
In this same vein, @comp.com is the default used by at least one spam
software package. Domain comp.com is registered to one of our
clients, but they have nothing to do with the spams - and we and they
don't need to hear about them.