After adding new domain name to your Office 365 account, you can assign it to existing Office 365 users. When you sign up for Office 365 account and create new users, the users will have email address of company-name.onmicrosoft.com domain name. After adding the domain name, you can change the email address of users to yourdomain.com. In this post, I will show steps to change domain name of multiple users in Office 365.
Change Domain Name of Multiple Users in Office 365
Log on to Office 365 portal. Go to USERS > Active Users.
Select multiple users as shown above and click Edit.
In the details option under Domain, choose mustbegeek.com or your domain name. Click next couple of times and click Finish.
You can view the new domain name under user name column as shown above. In this way you can change domain name of multiple users in Office 365.