David Cottle:
> >>>>>> Received: from server.engineering.idb (unknown [127.0.0.1])
> >>>>>> by server.engineering.idb (Postfix) with ESMTP id C3F5B13C002D
> >>>>>> for <[email protected]>; Sun, 11 Jan 2009 23:43:36 +0000
...
> > THIS WAS MAIL FOR [email protected].
>
> The postmaster address on every domain exists but does not accept mail
> it will bounce.
This was mail for WEBMASTER, now being returned to the sender.
If you have a non-functional postmaster address, that is sufficient
grounds for getting your entire domains blacklisted.
Wietse