We have migrated a client from @example.co.uk and on-premises Exchange Server 2010 to @example.com and Office 365.
We are keeping the old Exchange server running for the time being in case any further data needs to be migrated.
We need to prevent AD domain-connected PCs' email apps (Microsoft Outlook, etc) from Autodiscovering to the old Exchange server. Thus far, I have done the following which hasn't worked:
- Used EMS to set the CAS' Autodiscover service internal URI to null.
- Used ADSI Edit to delete
CN=%Exchange server hostname%,CN=Autodiscover,CN=Protocols,CN=%Exchange server hostname%,CN=Servers,CN=Exchange Administrative Group (FYDIBOHF23SPDLT),CN=Administrative Groups,CN=%AD DS NetBIOS domain name%,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=%AD DS DNS middle-level domain name%,DC=%AD DS DNS top-level domain name%.
- Used AD UC to reconfigure an AD user account clearing the attributes
Ideally, I don't want to:
- Disable the Exchange Windows services.
- Disable the Exchange user mailboxes.
- Create registry entries defining the Autodiscover behavior (excluding SCP lookup, etc) on the clients.
- Delete the IIS virtual directories.
What has to be done to achieve this?