troubleshooting Question

Cannot open many mailboxes in Outlook simultaneously

Avatar of David Haycox
David HaycoxFlag for United Kingdom of Great Britain and Northern Ireland asked on
9 Comments1 Solution8694 ViewsLast Modified:
We are running a new, clean install of Exchange 2013.  One user has the requirement to be able to access all 50 other user mailboxes from a single Outlook client (I know this is not recommended, and why - but the user has a business need for this so if possible we'd like to make it happen).

The user sees this error message when trying to open some of the mailboxes, however:

"The set of folders cannot be opened. 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."

Previously (in Exchange 2007) we have worked around this by removing the MAPI session limit ( but I understand this is dealt with quite differently in Exchange 2013, with throttling.

I have followed the instructions to create and assign a new policy found here - but this has had no effect.

Ignoring any potential performance issues (the server is hosted on Amazon Web Services and can be upgraded easily if more resources are required), how can we disable this limit, either for one or all users?

If possible step-by-step instructions would be great.  Thanks in advance for any assistance!
David Haycox
Consultant Engineer

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