How to add an alias to an Office 365 account
Add an alias to a user's Office 365 account
1. Sign in to the Office 365 portal.
2. In the header, click Admin.
3. In the left pane, click Users, and then click Active users.
4. In the list of users, select the user to whom you want to add an alias email address
5. Click on edit in the Username/Email & Aliases Tab.
6.Add the User name for Alias and Click on ADD.
7.Once the Alias is added, the primary ID could be selected.