An Exchange Server 2007 Client Access server responds slowly or stops responding when users try to synchronize Exchange ActiveSync devices with their mailboxes

When users try to synchronize Exchange ActiveSync (EAS) devices with their mailboxes in Microsoft Exchange Server 2007 environments, they encounter retryable errors. Additionally, the Microsoft Exchange Server 2007 Client Access server responds slowly or stops responding.

This issue occurs because EAS devices make continuous retries when they encounter retryable errors during the synchronization. This causes redundant communication to the Client Access server.

To resolve this issue, install the following update rollup:

Note�After you apply this update rollup, the Exchange Server�2007 server will drop EAS sessions if the number of sessions for a user exceeds the session limit. When the number of sessions is dropped lower than the limit, new requests can be automatically processed.

Registry key information

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base: After you apply this update rollup, to configure the EAS session limit on the Exchange Server�2007 server, following these steps:�

1. Click Start, click Run, type regedit in the Open box, and then click OK.
2. Locate and then select the following registry subkey:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\ParametersSystem
3. On the Edit menu, point to New, and then click DWORD (32-bit) value.
4. Type Maximum Allowed EAS Sessions Per User, and then press ENTER.
5. Right-click Maximum Allowed EAS Sessions Per User, and then click Modify.
6. In the Value data�box, type CustomValue,�and then click�OK.
7. Exit Registry Editor.

Note By default, the limit is 16.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

For more information about EAS, visit the following Microsoft website: