Exchange Server 2007: How to turn off the Back Pressure feature on transport servers

by Bharat Suneja on March 29, 2007

In reference to previous post titled “Exchange Server 2007 Transport: 452 4.3.1 Insufficient system resources“, the Back Pressure feature, that detects resource pressure on Exchange Server 2007 transport servers and stops accepting new message submission if low on resources, can be turned off. Here’s how to do it:

  1. Open the EdgeTransport.exe.config file from \Exchange Server\bin directory using notepad
  2. Add the following key+value pair:
    <add key=”EnableResourceMonitoring” value=”false” />
  3. Save file
  4. Restart the Microsoft Exchange Transport Service (MSExchangeTransport):
    Restart-Service MSExchangeTransport

{ 6 comments… read them below or add one }

1 Ben Winzenz March 29, 2007 at 3:50 pm

This is good information, but it really should be stressed that turning off back pressure is not recommended. It is enabled so that Exchange can detect and prevent problems. More information on Back Pressure can be found here:
http://technet.microsoft.com/en-us/library/bb201658.aspx

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2 Bharat Suneja March 29, 2007 at 6:17 pm

Certainly, it’s not recommended to turn off Back Pressure – it’s one of the smarter things Microsoft has done with Receive Connectors (aka “SMTP virtual servers” in previous versions), and the transport.

Back Pressure parameters can be tweaked, as mentioned in the earlier post linked in the above one.

Nevertheless, this comes in handy when you want to turn on transport/message submission asap – as the last option perhaps.

Bharat

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3 dabash March 15, 2010 at 4:46 am

thanks for you its really nice trick , i use it today until i manage to clean hard disk , so users did not feel there is any email blocked
after i clean the hard disk i return the EdgeTransport.exe.config file as before

thanks again

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4 Patrick Feller October 28, 2010 at 2:39 pm

I had this same issue but when I backed up the exchange database it cleared the logs and the transport service was then able to start normally.

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5 rawbar January 1, 2012 at 9:20 am

I just had to turn this off myself, but I don’t see anything wrong with the server as far as resources go. Exchange 2010 is running in a Hyper-V VM, but CPU, memory and disk space are all good.

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6 rawbar January 1, 2012 at 9:54 am

Update: Found this digging through the event log
The following resources are under pressure: Queue database and disk space (“C:\Program Files\Microsoft\Exchange Server\V14\TransportRoles\data\Queue\mail.que”) = 97% [Medium] [Normal=95% Medium=97% High=99%] Queue database logging disk space (“C:\Program Files\Microsoft\Exchange Server\V14\TransportRoles\data\Queue\”) = 97% [Medium] [Normal=95% Medium=97% High=99%] The following components are disabled due to back pressure: Inbound mail submission from Hub Transport servers Inbound mail submission from the Internet Mail submission from Pickup directory Mail submission from Replay directory Mail submission from Mailbox server Mail delivery to remote domains Loading of e-mail from the queuing database (if available) The following resources are in normal state: Version buckets = 0 [Normal] [Normal=80 Medium=120 High=200] Private bytes = 0% [Normal] [Normal=71% Medium=73% High=75%] Physical memory load = 29% [limit is 94% to start dehydrating messages.] Batch Point = 0 [Normal] [Normal=1000 Medium=2000 High=4000] Submission Queue = 0 [Normal] [Normal=1000 Medium=2000 High=4000]

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