After updating Exchange 2010 from SP3 Update 2 to Update 5, a change has occurred for users with SendAs and Full Access to other mailboxes. Version 14.3 (build 123.4).
Before the Update, after giving a user these permissions to another user's mailbox, the mailbox would show in their Outlook 2010 client, and everything worked as expected.
After Update 5 was installed, when users select the other user's mailbox, they get a message "the folders are not available," or the connection to the Exchange server is not working." They can access their own mailbox with no issues.
The other mailbox has to be added to the Outlook client via Account Settings, Account Settings, Change, More Settings, Advanced tab, Add the other mailbox. The mailbox then shows up twice on the client, but only the one that has been added works, the original still gives the same error.
Lou H.