Office 365 user names with ADSync have the OnMicrosoft.com Domain

So I have been working on a Exchange 2016/Office 365 Hybrid solution. Part of the setup is to install and configure ADSync which depending on the day of the week it could either be a Office 365 or Azure Utility. I have honestly installed this tool several times, and it is never in the same place every time I need to download it.

Once ADSync is installed, It will sync your Local AD Users to Office 365/Azure AD. Depending on how you configure the Sync, it could synchronize the whole AD Forrest, an OU (or Multiple OUs), or a Group. In my case I selected 1 of our OUs.

Within 30 minutes all of my users in that OU were sync'd with Office 365/Azure AD. However all of my users had a @company.OnMicrosoft.com user name. Normally this would not be a problem, however I am sure this would be confusing to some users. I also noticed that the usernames were also not consistent either.  Some of them looked like this:

shinnk@companyname.OnMicrosoft.com

or

Ken.Shinn@Companyname.OnMicrosoft.com

After scouring the internet I found nothing on how to fix this for my users. I was just about to open a ticket with Office 365 Support when I found a Technet Article that talked about how the usernames are generated when using ADSync.

To Paraphrase the article, the username in Office 365 is set by the user's Alias set in Exchange. Which led me to believe that we really have some inconsistent naming going on at my office but that is for another day.

The Article also covered how to change the user names. This let me to believe that I could use this same method for changing the domain name as well, and it worked!

Here is what you will need to do

Connect to Office 365:

Connect-MsolService

Then use this command:


Set-MsolUserPrincipalName -UserPrincipalName Alias@companyname.onmicrosoft.com -NewUserPrincipalName FirstName.LastName@domain.com

If you don't get an error message then you should be able to click the refresh button in Office 365 for the user account and you will see the new name.