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farism's avatar
farism
Copper Contributor
Sep 28, 2020

Using another UPN to login to Exchange Online

Hi, 

On my premise, users are using the UPN to login @mycompany.com , we have another small company called smallcom.com, in my premise, I added an extra  UPN for them so they can log in using alias@smallcom.com as everything is hosted in my datacenter.

I am moving to Office 365, and don't know how to add additional UPN to the user on my tenant as once I add the additional UPN, the login process keeps failing.

Note: I added the smallcom.com as domain and validate it.

so is this a possible scenario 

  • There's no such thing as additional/extra UPN in Exchange Online. You should have no problem adding another domain and changing the user's UPN to match said domain though. And if needed you can redirect the sign-in process to on-premises, so that users keep the same login experience.

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