Behavior:
Connect to mail is using a impersonator user for accessing the email acounts. Sometime it is neccessary to check the impersonation.
Solution:
The domain data is NOT stored within Connect To Mail but it uses the impersonation feature of Exchange Server.
To test the functionality on the client side, please download the following tool:
https://github.com/dseph/EwsEditor/releases/download/1.23/EwsEditor.1.23.-.bin.zip
It's open source and uses exactly the same method to access the Exchange account. Start the tool and enter the following:
Once a successful connection can be established with the tool, Connect to Mail should function properly.
Otherwise, the Exchange Server is not set correctly, ie this is not Connect to Mail problem. The following should also be helpful for further research:
http://calendarservermigration.blogspot.de/2007/08/exchange-2007-impersonation-debugging.html
If the connection can not be established successfully, then please send us the Connect to Mail Log. You have to activate it first. For this purpose please note the following FAQ article:
Activate the debug logging of the system