Delivery Status Notification (Failure) mspop3connector.{validemail

[LaviN]

The mail which are downloaded via the POP3 Connector are being returned as non-deliverable with below information:

Delivery to the following recipients failed.

mspop3connector.abc@mydomain

Even when abc@mydomain is a valid email address on my exchange server.

Things were fine before, i don't know what went wrong suddenly. I have tied tricking the server by entering SMTP address for the user of mspop3connector.abc@mydomain and the mail is getting delivered without any issue. Any idea what might be wrong???

[NavinS]

I think your POP3 Connector might have got corrupted some how and you will have to re-register it. You just have to run \Program Files\Microsoft Windows Small Business Server\Networking\POP3\imbreg.exe for re-registering POP3 Connector. Just give it a try and let me know if that helps.

[jjinnapoli]

Although this is a very old problem, it's one that just started popping up for me late last year and the imbreg.exe 'fix' did not work for me, so I imagine that some people might still experience this problem. I ultimately solved the problem and wanted to share my solution. I finally realized that the problem appeared to start not long after I installed a new antivirus on the server. I won't be specific on the name of the antivirus because I don't want to bag on any particular vendor. The solution to the mspop3connector prefix problem is to exclude the C:\Program Files\Microsoft Windows Small Business Server directory from active or realtime scans. The reason is that email coming in through the POP3 connector passes through the following directory:
C:\Program Files\Microsoft Windows Small Business Server\Networking\POP3\Incoming Mail

It appears that my antivirus was holding this file while scanning, and causing an error to kick out, resulting in the email getting 'stuck' at the mspop3connector stage and getting kicked back to the sender.

I suppose that the realtime scanning exclusion could be more specific to exclude only this directory, but just to avoid any other possible future 'collisions' I cut the path off at the root of the SBS directory.