I am currently in the middle of an Exchange migration from 2010 to 2013. Everything has gone perfectly until this point.
I migrated a user over to the new server with no issue. I can send, receive, and access through OWA. However, if I create a new Outlook profile, with the Server set as the FQDN (server.internaldomain.local), place the user name (test), and check name, it will find the user and underline the Server and User Name since they've been resolved. This is all normal, but when I go to open Outlook, I get the error:
Cannot start Microsoft Outlook. Cannot open the Outlook window. The set of folders cannot be opened. You must connect to Microsoft Exchange with the current profile before you can synchronize your folders with your Outlook data file (.ost).
If I log in as the user and it auto-creates the profile when first opening Outlook, it works with no issues. It connects to mail.externaldomain.com as the server and I can send and receive mail.
1. I have not modified any certificates
2. I have not modified the autodiscoverInternal record for the new server