After you set up your custom domain in Office 365 (like fourthcoffee.com, for example), you can change the default domain used for new email addresses when you add users in Office 365 Small Business or add users in Office 365 Enterprise or Office 365 Midsize Business.
To change the default domain:
- Go to your organization’s Office 365 profile by doing one of the following:
- If you’re using Office 365 Small Business, on the Admin page, in the upper right, click your organization’s name.
Note If the Getting Started pane is open on the Admin page, your organization name is just below it on the right (not in the upper right).
- Otherwise, go to Admin > Office 365, and then, in the upper right, click your organization’s name.
- Scroll down the list of profile information to the default domain setting.
- Choose a new default domain from the drop-down list, and then save your changes.
Note In other Microsoft cloud services, such as BPOS, there was also a concept of a primary domain, which was also the default domain. Office 365 does not have primary domains.