May 01 2017 12:50 AM
To Prepare for Office 365 Migration you need to add the missing 'UPN Suffixes'.
The following example demonstrates how to create a new UPN suffix for the users in the ThatLazyAdmin forest:
Lets Start by running:
Import-Module ActiveDirectory
Then run :
Get-AdForest | Set-ADForest -UPNSuffixes @{Add="ThatLazyAdmin.com"}
Lets verify the new UPN in Active Directory Users and Computers
There you go.