Exchange 2010 sp3 cu4 with Exchange 2013 CU8.
We switched autodiscover and CAS dns record webmail to the Exchange 2013 server.
All works well for users on Exchange 2010 and also some test users on Exchange 2013.
Now we have a shared mailbox/user mailbox that someone has full access to, 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 (full access on the mailbox)
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."
I've found this > https://support.microsoft.com/en-us/kb/2834139 but this applies for users on 2013 that not can open a 2010 mailbox, our situation is the other way around so not applies to us.
- Edited by dirkverhagen123 13 hours 49 minutes ago