Issue with Update Rollup 5 for Exchange 2010 SP3 - Mailboxes that were auto mapped not working

Question

Below is  my response in another thread but creating a new one in the hopes that someone has the same issue and a solution besides mine below.
Ever since we installed Update Rollup 5 for SP3 Exchange 2010 mailboxes that were auto mapped are not accessible. They all get the same error.
Cannot expand the folder. The set of folders cannot be opened. The attempt to log on to the Microsoft Exchange has failed.
What I have been doing is removing the users permission, then adding them back using the noautomap switch in Powershell. After doing that, the user manually adds the mailbox and all is well.
Just a note here, I suspect it may have something to do with the version of Outlook 2010. We are running an older version here. I think only SP1 with no other incremental updates. Office is up to SP2. Also, one of the users I was working with could not access
the mailbox no matter what we tried but she can walk over to another workstation and open Outlook and access the very same mailbox so that pretty much proves its software related particularly with Outlook.
I cannot reproduce the problem on a workstation (XP) with a newer version of Outlook.
This has been wearing me out and I suspected the Update Rollup all long. Now I am confident as others are having the same problem. If you find out anything on how to fix this other than the steps above, let me know.

Answer 1

Not sure why it was suggested to use the auto mapping feature to grant permissions because that is the component that is causing the issue. Also, there is nothing wrong with the auto configuration because the user can access their own mailbox just fine and
also select mailboxes in their Outlook that were NOT auto mapped.
With that said, here is how I fixed them all.
Remove the permissions using the Exchange Console. Don't forget Send As
Wait about 15 minutes. The mailbox should disappear from the users Outlook
Open an Exchange PowerShell window and run the following command:
.\add-mailboxpermissionsnoautomap.ps1 -Identity mailbox -User user -AccessRights FullAccess
Have the user add the mailbox to their Outlook using the manual process.
All is well....
If you don't have the PS script add-mailboxpermissionsnoautomap.ps1, you can download it. I stumbled across it a few years ago and use it all the time. If you can't find it, just use the Exchange built in command for adding mailbox folder permissions but
specify automap $false.
The idea here is to grant the user access without auto mapping.