UPN not matching email address - Office 365

Hi Experts, have a Hybrid O365 scenario where domain is .local and upns will not match with email addresses. Will there be any issues when using dirsync to sync users? Forest and domain is 2003. On prem Exchange is Exchange 2010 SP3

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Vasil Michev (MVP)Commented:
Depending on how tech savvy your end users are. In my experience, most cannot really make the difference between an UPN and SMTP/SIP address, so this will undoubtedly generate some "cannot login" incidents. Any particular reason you cant just add additional suffix(es) and update the UPNs?

Also, if you ever decide to go with AD FS, you will need a proper UPN (or you will need to overcomplicate things a lot by using alternate IDs)
abhijitm00Author Commented:
I am comfortable adding the upns for users but the "cannnot login" incidents are what are worrisome
abhijitm00Author Commented:
Is there way to dirsync users to O365 and change the email to point to their vanity domain? Thanks
Vasil Michev (MVP)Commented:
You can change the SMTP address after you sync the users by running:

Set-Mailbox user@domain.onmicrosoft.com -WindowsEmailAddress user@domain.com

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Similarly, you can change the UPN by using:

Set-MsolUserPrincipalName -UserPrincipalName user@domain.onmicrosoft.com -NewUserPrincipalName user@domain.com

Open in new window

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