Exchange Recipient Filter makes PopGrabber slow to a crawl

[scotbw]

One more issue I need to post:

When I have the Exchange Recipient Filter enabled on the SMTP connector, each SMTP transaction where Exchange rejects the recipient (since it's not a valid recipient on the server) takes 8-12 seconds, making PopGrabber almost unusable on large mailboxes.  When downloading a couple of thousand messages, lots of the messages will be reject messages, and those recipients don't exist, and when it takes that long to handle a single message, the POP mailbox backs up very quickly.

Now that I've turned off the Recipient filtering, it runs as I would expect - 5 messages/second or so - but I have over 3600 SMTP queues (and counting, with another 3000 POP messages to download) on my Exchange Server trying to send out "bad recipient" messages from these messages.

What would cause PopGrabber to slow to a crawl like that when trying to send a bad recipient message to Exchange?

Thanks,

[Eclarsys Support]

Hello,

This probably happens because Exchange drops the connection when filtering the recipient and PopGrabber is still waiting for a response and does not continue until a timeout occurs.

Please configure Exchange so it does not drop the connection, but instead rejects the message correctly.

Which Exchange version are you using?

Regards,

Eclarsys Support

[scotbw]

This is Exchange 2003 SP2, part of Small Business Server 2003.  What would be the configuration for Exchange to reject messages "correctly"?  PopGrabber gets the 5.x.x invalid recipient code from Exchange and shows it in the log, so I would have thought it was doing what it was supposed to.

Thanks,

- Scot

[Eclarsys Support]

You should not disable the recipient filtering, you should only configure Exchange not to drop the connection when filtering messages (see the attached screenshot). This only applies to sender recipient, but it may also be the cause of the problems you are having.

In the PopGrabber global account configuration, setup PopGrabber (under Actions - Server Rejects Recipient) to either redirect these messages to the administrator or to delete them, depending on what you would like to do.

If PopGrabber still takes too long to download messages when these settings are correct, please send us a few lines of the log file so we can trace the source of the problem.

Regards,

Eclarsys Support

[Eclarsys Support]

Hi again,

looking further into this problem, we found out another possible cause. There is a feature (called tar pitting) in the SMTP Service from windows with slows down the communication if an SMTP client constantly tries to deliver emails to invalid recipients.

This would cause a problem similar to the one you are having. This feature is disabled by default, but it may be enabled in your server.

Verify if you have an entry for TarpitTime in the registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SMTPSVC\Parameters. This value sets the number of seconds the SMTP server delays the communication if an invalid recipient is specified in the SMTP session.

You can find more about this feature here:
http://support.microsoft.com/default.aspx?kbid=842851

Let us know if this helps.