It is easy to Set the Primary Email Address on Office 365 with PowerShell.
It’s done with the Set-Mailbox cmdlet. The primary address is set by using “SMTP” in uppercase in the email address.
You do have to be slightly careful as using the Set-Mailbox cmdlet to change the primary address will remove all of the other aliases. So if you have any, they must be included with the command.
I have made this process really easy for you (and myself). Enter the details of the mailbox you want to change below and it will generate the required Set-Mailbox command for you to copy and paste into a PowerShell session.
I have also included all the required PowerShell to connect to Office 365 and disconnect again.
Set the Primary Email Address on Office 365 using PowershellMailbox Identity:
Primary SMTP Address(e.g. [email protected]):
Additional email Aliases(e.g. [email protected],[email protected]):
PowerShell to Copy/Paste
Using the generated script you will get output like this:
Set the Primary Email Address on Office 365 when the user is being managed by the local active directory
The instructions above will work if the user that you are attempting to change is cloud managed, but if it is being synced from your local active directory then it will be out of the write scope of Office 365 and it will not work. If that is the case then follow the instructions on this page: