>All I am going by, is that on my list, this only happens once, when people
>try to subscribe, and the confirmation comes back, because their mailer's
>are messed.  If you send mail to this address it too will bounce.  I found
>this out by mailing the sys-admin about one of these bounces.  It turns
>out that the person/address in question, was trying to subscribe with
>[log in to unmask], but she was still set up (on the server end) as
>[log in to unmask]  After the sysadmin got back to me, I mailed the
>person with the proper address, and she explained it.  She waited a few
>days for her server to be corrected, and subscribed with no problem.
>
>Since then, I just write these off as subscribers with messed mail
>programs.

But this wasn't a messed-up mail program, it was a clueless subscriber.
She subscribed (successfully) with an invalid email address, which began
bouncing immediately.  The same thing can happen if a subscriber transposes
two characters when typing their email address, or a host of other ways.
It's not the mail program's fault.

Sherry