Your server administrator has limited the number of items you can open simultaneously

After performing updates on out internal remote desktop server I started experiencing issues with Outlook 2013.  Our remote desktop server is configured to not time out sessions, so a session could remain active for a long time.  Every couple of days Outlook would stop opening emails, however simply closing and reopening Outlook would fix the issue.  I decided to finally resolve the problem.

The error the Outlook would give is:

Your server administrator has limited the number of items you can open simultaneously.  Try closing messages you have opened or removing attachments and images from unsent messages you are composing.

Your server administrator has limited the number of items you can open simultaneously

After performing some testing it appeared the issue only occurred when cached mode was turned off.

I logged into the Exchange server to see if there was any further clues.  I found the following event log message:

Event ID: 9646

Mapi session /0=First Organization/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=Mailbox name with client type MoMT exceeded the maximum of 250 objects of type Message.

MAPI session error

 

The issue was being caused by the per session MAPI limit that was configured on the Exchange 2013 server.  By default the limit is set to 250.

To increase the limit perform the following

  1. Log into the Exchange server
  2. Open the registry editor
  3. Goto the following key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\ParametersSystem
  4. Right click on ParameterSystem and select new, then select key
  5. Rename the new key to MaxObjsPerMapiSession
  6. Right click on MaxObjsPerMapiSession and select new, then select DWORD (32-bit) Value
  7. Rename the new DWORD value to objtMessage
  8. Change the value to a higher number (I set mine to 1500)
  9. Restart the Information Store service

After making the above changes I had no further issues.  Not sure why the problem only started occurring after performing Windows Updates.


   4 Comments


  1. Mario
      10/21/2015

    Just a correction. The event is 9646 not 9446.

    • gordoncarr
        10/23/2015

      Thanks. I have updated the article.

  2. Robert
      10/27/2015

    This seemed to have worked with Exchange 2010 but does not work with Exchange 2016.

  3. Scarsick
      01/14/2016

    Addins which scan through messages (as part of a cleanup action for example) cause this as well. Outlook (or Exchange) marks the messages scanned as open. If the threshold then exceeds 250 messages, this error is logged.

Leave a Reply

Your email address will not be published. Required fields are marked *