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I have Exchange2010 client is outlook2010. We have a user who has about 7 additional mailboxes due to her role. She is hitting the MAPI limit of 500 connections for "ObjectFolder"

Event log 9646 is generated.

I have tried to apply the fix of creating a registry key called "MaxObjsPerMapiSession" as per the Microsoft KB in \\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\ParametersSystem. I have restarted the info store but we are stil seeing Event 9646 errors for this user.

I need to up the limit for this user (or globally) I cannot remove her additional mailboxes. Any suggestions.

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Just to clarify what you did, after creating the MaxObjsPerMapiSession, did you also create a new click DWORD Value and setting the value name "objtFolder" with the actual value anything above 500? ( - some additional notes) – Cold T Jan 9 '12 at 10:22
Yes sorry. I Created the Dword and set it to 1000, – t1nt1n Jan 9 '12 at 10:24
Curious... Do the additional mailboxes show up in Outlook Web Access? – ewwhite Jan 9 '12 at 13:07
@ewwhite No they do not. As OWA cannot see additional mailboxes unless you use the "Select Mailbox Feature" – t1nt1n Jan 9 '12 at 13:12
Oh, I was thinking you were enabling "full mailbox access" via the Exchange management console. That will place the other mailboxes in the user's left pane, even on OWA. – ewwhite Jan 9 '12 at 13:14
up vote 1 down vote accepted

The Soloution as in my Quesion as to reg key \HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\ParametersSystem. But this needed a full reboot of the server not just a restart of the Info stor as per the MS artical.

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