Take Care With Exchange 2010 Throttling Policies

Many of my clients are currently evaluating Exchange 2010 for their production environments. While they probably won’t be implementing for a little time yet (average target dates are in Q4 for most clients I talk to), they are beginning to see different switches and settings that need to be tweaked from their defaults.  One of those settings is the native Throttling Policies that Exchange 2010 puts into effect to limit how much of various Exchange resources other applications are permitted to use.

Brian Desmond wrote a great article (you can read it here) that goes into detail about one potential problem that these limits impose.  Since the Throttling Policies are designed to stop individual client applications (among other things) from using up all the resources of an Exchange Server, they can impact 3rd-Party tools just as much as POP, IMAP and other mail client software.  In Brian’s article, he brings up the difficulties that Blackberry Enterprise Server (BES) runs into with the default policies, as they would normally hamstring BES’s ability to use a single account to ferry messages back and forth between Blackberry devices and the Exchange Server itself. 

In this case, what applies to the BES server can also impact other 3rd-Party applications that need to access an Exchange database via a client connection.  For example, archiving systems not using the new native tools may be working via a Journaling Mailbox or other single-account connection system. This means that the policies, as set up by default, would severely hamper the ability of the archiving system to get the data from the Exchange Server and into the archive solution.  Using the native archiving and compliance tools will help fix this, but many clients have invested a huge amount of time and money in setting up existing solutions. This means they face the choice between paying and implementing for an upgrade to the 3rd-Party system, versus completely re-engineering their archiving and compliance systems to switch to the native tools. 

Also, consider periodic mass-connectivity.  Anti-virus and other scanning tools may periodically connect to the exchange system using client connectivity, as would some 3-rd Party search and indexing systems.  Both of these will most likely not be hit by the policy limits, but could be if they do a mass-crawl. Careful evaluation of all systems that use client connections is necessary to eliminate any issues before they start generating client complaints.

Luckily, it is not difficult to change the Throttling Polices in Exchange 2010.  Brian’s article offers a great explanation of it, and of course Microsoft TechNET has a full set of details.  Once you determine which applications may need extended client access to the Exchange Server, you can set up custom policies for those applications and the accounts they use.