We have a shared mailbox from Exchange 2010 that we have migrated over to our 2013 environment. After the migration, users on 2010 can no longer open the mailbox via Outlook. They have all the proper permissions.
We are using NTLM only to authenticate. I've also set changed the shared mailbox to a 'shared mailbox' in Exchange 2013 but users still can't open it.
They recieve "Cannot open the folder. The set of folders cannot be opened. Microsoft Exchange is not available. Either there are network problems or the Exchange server is down for maintenance."