SCENARIO
You’re managing Office 365 and want to do Powershell quieries against the on-premise Active Directory
PROBLEM
The problem is that Office 365 cmdlets like “get-msoluser” always gives you the users userprincipalname (UPN) because that is all that Office 365 cares about. But when you want to query the local on-premise Active Directory with “get-aduser” it doesn’t recognise the UPN when searching for users.
SOLUTION
The solution is adding it as a filter like this, where $MSOLUPN is the UPN you get from “get-msoluser“:
Get-ADUser -Filter { UserPrincipalName -Eq $MSOLUPN }
Again, this is pretty basic stuff, but still something you need to know and use all the time.