When migrating to Exchange 2016, you may come across the following problem:
For smartphones or other ActiveSync devices, the domain was previously optional and was left blank, as can be seen in the following screenshot of an iPhone:
If the CAS proxy function is now used for coexistence between Exchange 2010/2013 and Exchange 2016, the ActiveSync devices may no longer work. As soon as the ActiveSync connection runs via the Exchange 2016 server, the domain must be specified:
Apparently, the authentication methods on the Exchange 2010/2013 servers are identical to those of Exchange 2016 servers. Nevertheless, the ActiveSync devices only work after the domain has been stored in the profile.
To ensure that the ActiveSync devices continue to function during the coexistence of the Exchange servers or after the migration, the Exchange 2016 configuration can be adapted.
To do this, the virtual directory "Microsoft-Server-ActiveSync" of the "Default Website" is selected in the IIS Manager on the Exchange 2016 servers and the authentication settings are opened:
Only "Standard authentication" should be activated in the authentication settings. The standard authentication can now be edited:
In the dialog that opens, you can now specify the default domain and the area. However, a little caution is required here. A "Backshlash (\) is entered as the default domain and the internal domain name as the scope:
In this example, the Active Directory is called "frankysweb.local", so "frankysweb.local" is specified as the domain. The default domain is the backshlash.
Finally, the IIS should be restarted:
iisreset
ActiveSync devices can now also connect to Exchange 2016 without specifying the domain. This is quite helpful if you do not want to reconfigure all smartphones. This setting should be checked accordingly before the CAS proxy function is activated during migration.