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How to stop Outlook from using Public Folders.

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While working on a case, where Exchange 2010 users randomly get pop-up message:

"The Exchange administrator has made a change that requires you quit and restart
Outlook."

We verify that the affected users have not been moved, and not changes were done on Exchange while
this message pops up.

After a few month of trying to collect data we found that Outlook was trying to contact public folders, and the customer do not really used public folders and we found a registry key that was not documented that is able to stop Outlook from trying to connect to public folders.

Key:

HKCU\Software\Microsoft\Exchange\Setup\

DWORD Value:

HasPublicFolders

HasPublicFolders = 0

After settings this registry key we no longer get reports of users getting the pop up to ask them to restart Outlook, unless the mailbox is really moved.

Since I know that case I have use this key in other situation that help isolate if issue is related to public folder access.

Outlook client applications cannot connect to public folders after you install Exchange Server 2010 SP1
https://support.microsoft.com/kb/2535105

FIX: Application may stop responding after several HTTP requests are aborted if you use the HttpWebRequest class to send requests in the .NET Framework
https://support.microsoft.com/kb/2497453

In KB 2535105, If you are affected you may receive different symptoms such as:

Outlook getting prompted
for credentials

Connection failing over
from TCP/IP (MAPI) to HTTPS (Outlook Anywhere / RPC-HTTP)

High CPU usage on CAS
due to public folder referral

Using the registry key to stop Outlook from using Public folder the Outlook client symptom is workaround. (A good way to isolated if those issues is related to public folder
access.)

If this key help you or other scenario that you find this key helpful please leave a comment.

Thanks,

John