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Sunday, February 10, 2008


Exchange Server 2007 SP1: The most obscure (but relevant) changes

Posted by Bharat Suneja at 7:31 AM
Recently I was asked by a fellow MCT (and now Exchange MVP) to list 3 most obscure (but relevant) changes in Exchange Server 2007 SP1. The first thing that came to mind was the change made to Back Pressure settings.

Back Pressure stops inbound mailflow on transport servers if system resources fall below a certain level. In Exchange Server 2007 RTM, the threshold for free disk space was 4 Gigs - if you had less, Back Pressure (yes, there have been jokes about the name of this feature... ) stops inbound mailflow and throws a 452 4.3.1 Insufficient system resources error on mail submission. Read previous post Exchange Server 2007 Transport: 452 4.3.1 Insufficient system resources for my experience with this.

In SP1, the threshold has been reduced to a much more realistic level of 500 Mb. I can probably live with that.

I later posted about turning Back Pressure off - not necessarily something I recommend in production. However, in test environments (particularly in virtual server environments with disks created to be the smallest size possible to allow installation of Windows Server and Exchange... ) this generally makes sense.

Related posts:
- Exchange Server 2007 Transport: 452 4.3.1 Insufficient system resources
- Exchange Server 2007: How to turn off the Back Pressure feature on transport servers

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February 11, 2008 8:33 PM
Blogger ROSH said...


Some of the WMI Classes present in Exchange 2003 are Missing in Exchange 2007 such as for eg. Win32_PerfRawData_MSExchangeMTA_MSExchan
geMTAConnections,Win32_PerfRawData_MSExchangeMTA_MSExchangeMTA,Win32_PerfRawData_SMTPSVC_SMTPServer etc..
is there any command or utility to reregister the above WMI Classes in Exchange 2007 ???
Plz help

Thanks & Rgds

February 21, 2008 9:46 AM
Anonymous Maximz Zinchenko MVP:Exchange said...

Actually I'd say - Microsoft never recommended to turn off the Back Pressure feature in any prodution environment, but rather to tune it up to your organization "internet visibility" and incoming smtp traffic value. This would be the best step but not letting your mail system down due to an attack.


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