I'm currently working on converting "In the Cloud" Office 365 accounts to Active Directory synced accounts. As a step in the process, I had to match the UPN suffix to match the "Username" or SMTP Value in Office 365.
Open the Active Directory Domains and Trusts snap-in.
In the left pane, right-click Active Directory Domains and Trusts and select Properties.
Under Alternate UPN suffixes, type the name of the suffix you want to add.
Click Add and OK.

I'm currently working on converting "In the Cloud" Office 365 accounts to Active Directory synced accounts. As a step in the process, I had to match the UPN suffix to match the "Username" or SMTP Value in Office 365.

Open the **Active Directory Domains and Trusts snap-in**.

In the left pane, **right-click Active Directory Domains and Trusts** and select **Properties**.

**Under Alternate UPN suffixes, type the name of the suffix you want to add**.

Click Add and **OK**.

Add alternative UPN suffix in Active Directory

David Galiata IT Consultant turned cybersecurity architect | Passionate about IT, cloud, and security. Always learning. Blogging about my adventures in the industry