Saturday, February 9, 2013

How to increase number of Open Items for Outlook 2010 users in Exchange 2010

Symptoms

Outlook error message
In Exchange 2010 when Microsoft Outlook users use Online Mode and open numbers of message windows, they may encounter an error stating the server administrator has limited the number of items you can open simultaneously. Below is the error message that will be displayed on the Outlook Client.





Exchange Server 2010 error message in event viewer
ID: 9646
Type: Error
Source: MSExchangeIS
Description:
Closing Mapi session "/o=Organization/ou=Administrative Group/cn=Recipients/cn=user" because it exceeded the maximum of 250 objects of type "objMessage".

Cause
This problem performs when a MAPI client tries to open more items than the default value of the objMessage. The default value is 250 objMessage.




Solution
To modify the items we can open i.e, "Open Item Limits" part. The detailed steps are below. Note if we want to modify the open item limits, we need to modify them on ALL Mailbox servers within any DAGs and client access arrays. If we don't make the same changes on all servers, the results will be inconsistent.

Start the registereditor on  the Exchange 2010 server.

  1. Start Registry Editor (regedit).
  2. Navigate to the following registry subkey:
    \\HKEY_LOCAL_MACHINE \SYSTEM\CurrentControlSet\Services\MSExchangeIS\ParametersSystem
  3. Right-click ParametersSystem, point to New, and then click Key.
    A new key is created in the console tree.
  4. Rename the key MaxObjsPerMapiSession, and then press Enter. 
  5. Right-click MaxObjsPerMapiSession, point to New, and then click DWORD (32-bit) Value.
    The new value is created in the result pane.
  6. Rename the key to <Object_type>, where <Object_type> is the name of the registry object type that you're modifying. For example, to modify the number of messages that can be opened, use objtMessage. Press Enter. 
  7. Right-click the newly created key, and then click Modify
  8. In the Value data box, type the number of objects that you want to limit this entry to, and then click OK. For example, type 2000 to increase the value for the object.
  9. Restart the Microsoft Exchange Information Store service.


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