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How to set maximum number of MAPI connections in exchange server 2007


Please let me know on How to set maximum number of MAPI connections in exchange server 2007?
We need to restrict some mailboxes from making multiple MAPI connections to mailbox server.

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8/22/2022 - Mon

What problem do you intend to solve with this kind of solution?

The maximum by default for all users is 32, and Outlook will make multiple MAPI connections to Exchange for legitimate reasons. That limit can be changed per CAS role, but it would affect all users connecting through that CAS.


We need to restrict MAPI conections created from end user PC's who are having multiple mailbox access.

We are suspecting that users wit multiple mailbox access wit cace mode enabled are having issues.

Yes, those issues that the users are having - what are those issues?

If you're seeing events about "User created more than 32 of objSession" or some such, reducing the MAPI session limit is only going to make that worse.

Outlook will try to connect as many mailboxes as you tell it to open, whether you have permission to them on the server or not, and as far as I know, there's no way to stop it from trying. And, as above, Outlook will make multiple MAPI connections to the server even with only one mailbox open, and that's normal behavior.
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Issue : User with multiple mailbox access over RPC over HTTPS access are complaining about slow performance of outlook. Soem times normal users with access to their primary mailbox are also observing the issue.

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Slow performance in Outlook is most likely caused by conditions of the database, conditions of the mailbox, or conditions of the items in the mailbox.

If you have corruption in the database, users on that database may experience slow access with Outlook. If a particular mailbox has a large number of corrupt items in it, the users who open that mailbox may experience bad performance, and that can also affect other mailboxes on the same database or server (especially when users are not using cached mode; online mode shifts a lot more load to the server). If a mailbox has a very large number of items in a folder (over 5,000, especially in a default folder like Inbox or Sent Items), or if a mailbox contains a very large number of folders (over 500), users who open this mailbox will definitely experience performance issues, though these conditions will be less likely to impact other mailboxes - unless there are many users with Outlook in online mode in an attempt to rectify performance, then you're adding server load.

Most likely, you have a combination of these conditions going on, to varying degrees.