How to troubleshoot the POP3 Connector in Windows Small Business Server 2003

Since occasionally conversation bubbles up on new SBS clients who use POP and transition to SMTP you likely will on occasion see errors in the monitoring reports related to the POP Connector.  This article expounds on this subject.

How to troubleshoot the POP3 Connector in Windows Small Business Server 2003

One interesting point I discovered while reading this today is that CDO (Collaborative Data Objects)  is used to retrieve and transfer the POP mail to the SMTP side of Exchange.  CDO is also mentioned in BlackBerry documentation for the current 4.1.6 upgrade under the directions of Windows patches recommended to be installed in preparation.

Exchange 2003 CDO Patch 6980.3 KB823343-x86

POP3 Connector overview

When you use the POP3 Connector to retrieve e-mail, the following mail-flow process occurs:

The Connector for POP3 Mailboxes service connects to and logs on to the remote POP3 server.

The Connector for POP3 Mailboxes service downloads e-mail messages and stores them in the following folder:

%PROGRAMFILES%\Microsoft Windows Small Business Server\\Networking\POP3\Incoming Mail

When all the e-mail has been downloaded from the remote POP3 server, Collaborative Data Objects (CDO) on the Windows Small Business Server-based computer retrieves the e-mail messages from the Incoming Mail folder. The headers of these e-mail messages are modified to indicate that the e-mail messages will be directed to a local Exchange mailbox, and then the e-mail messages are saved to the following folder:

%PROGRAMFILES%\Exchsrvr\Mailroot\vsi 1\PickUp

If CDO cannot move an e-mail message to the PickUp folder, the e-mail message is put in the following folder instead:

%PROGRAMFILES%\Microsoft Windows Small Business Server\\Networking\POP3\Failed Mail

If an e-mail message is corrupted, it may not be moved to the Failed Mail folder. In this scenario, the corrupted e-mail message remains in the Incoming Mail folder.

All the e-mail messages that are in the PickUp folder are processed by the local SMTP service and are delivered to the appropriate recipient.

When you use the POP3 Connector to retrieve e-mail messages, those e-mail messages are not processed by any of the following Microsoft Exchange Server 2003 components:

Recipient Filtering

Sender Filtering

Connection Filtering

The Intelligent Message Filter add-in

Because the POP3 Connector uses CDO to transfer e-mail messages to the SMTP PickUp folder, these e-mail messages bypass the filtering mechanisms that Exchange 2003 contains.


4 responses to “How to troubleshoot the POP3 Connector in Windows Small Business Server 2003

  1. I bow down to thy wisdom, knowledge, and kiss thy big juicy brain! Hail ‘o great one for surely I’m not worthy.

    Thank you VERY MUCH for this post. It helped me solve a problem I’ve spent countless hours on!

    • You have really done a fine bit of grovelling there 🙂 …thanks for the kudos.

      Its a big NET and I just try and tie my little part of research into it. Hope you browse around and find something else useful. Send some others this way too as this helps a lot when building interest and support.

  2. Hello Guys,
    someone experience Problems like this with SBS 2008?

    • not that I’ve heard of – in any case Exchange 2007 is a big update from the Exchange 2003 platform found in SBS 2003. Any similar problems will be addressed in entirely new ways within the program UI and Command Shell.

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