I am in the process of a 2010 to 2013 migration. The only issue I can't seem to manage is an authentication issue with Outlook 2010. My Outlook profile consists of my Exchange 2013 mailbox and a shared mailbox on Exchange 2010. Initially, Outlook was prompting for authentication to the Exchange 2010 mailbox. Regardless of whether I entered the correct credentials or simply cancelled the prompt, I still had full access to both mailboxes (including Public Folders on 2010). The authentication prompt was removed with the following command:
Get-OutlookAnywhere -Server my2013exchserver | Set-OutlookAnywhere -InternalClientsRequireSsl $true
The second issue I now have is the reverse of the above: an Exchange 2010 user is prompted for authentication to an Exchange 2013 mailbox. How do I begin to troubleshoot this problem - should I run the same command (above) on 2010? I don't quite understand how Outlook communicates with Exchange but I am thinking there is an incorrect setting on one of the Virtual Directories(?).
Many thanks.