Exchange 2010 and Outlook 2003 Slowness

It’s been a little while since I have had to migrate Exchange 2003 to 2010, and I ran into a familiar problem again – so I thought I would share.

I migrated a couple users over from the Exchange 2003 server onto the Exchange 2010 server, and the next day users were complaining of slowness.  It would take about 30 seconds or more for messages to be deleted, moved, and any sort of update to the mailbox.  It doesn’t seem like much, but when you are upgrading, and the new is slower than the old, the users notice.

It’s actually a know issue, and it has to do with the way that Outlook communicates with Exchange. Outlook 2003 polls the exchange server every 60 seconds for updates, and Exchange 2007 and below would send UDP notifications to the outlook clients – however, the UDP notifications are no longer part of Exchange 2010, causing outlook 2003 to have delays.  This issue doesn’t affect Outlook 2007 or 2010.

The ‘workaround’ method is to simply put the outlook account into cached mode by checking the box. This masks the problem, as the deletions, moves, and other handling of messages is first done in the .OST file. This is immediate, and then is updated on the exchange server during the next polling.


The solution on the server, however, is an update and a registry entry.

  • First, install Update Rollup 3 for Exchange Server 2010 SP1.
  • Next, open up the registry and browse to the following key. (you may need to create the ParamtersSystem key)
    • Subkey location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeRPC\ParametersSystem\
    • Add a new DWORD entry: EnablePushNotifications
    • Set the Value to 1

This should now speed up your outlook 2003 clients when connected to Exchange 2010.

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