E-mail works fine for days at a time, then all of a sudden we get NDRs on all mail destined for local accounts:
Arrival-Date: Fri, 5 Dec 2003 06:03:43 -0800
The NDR comes from the postmaster on our server, so it is getting that far. Also, we're still able to relay e-mail out to the rest of the Internet (to addresses not hosted on our server). It's worth pointing out that the only way to get that NDR is to provide a sender address that isn't local -- else the NDR gets it's own NDR in the badmail folder.
What can I do to fix this problem? Our only method of righting the problem up until now has been to restart the entire server -- stopping and restarting SMTP hasn't helped.
We are using Windows Server 2003 Web Edition built-in SMTP/POP3 on IIS6. There are three domains configured to the same IP.
Thank you very much for your time & Expert-ise!