Hello,
This is Michelle Wilbers of WhatHelps?
IPSwitch (IMail) provided us with the solution to this problem. We needed to
stop and disable Microsoft's Simple SMTP, which was running on the same
server.

Michelle

======================
> If you are NOT getting alot of bounces on your list, then for diagnostic
> purposes, assuming that the WHATHELPS. folks don't have any further
> insights, then temporary turn OFF the AUTO-DEL processing so that you can
> "see"  the full bounced e-mail.
>
> I suspect that this kind of mail is an "after hours" kind of bounce e.g.,
> some maintenance is taking place on the end-user's email system that
> inhibits his mail account from being confirmed as valid.
>
> /Pete