What is a domain and how do I use it in Office 365?

The part of your email address after the @ is your domain name. So, for example:

  • If your email address is joe@contoso.com, contoso.com is the domain name.

  • If your email address is joe@contoso.onmicrosoft.com, contoso.onmicrosoft.com is the domain name.

  • If you have a website at www.contoso.com, contoso.com is the domain name.

Note: If you just want to download and use Office 365 apps, like Outlook or Word, you don't need to add a domain, unless you want to have a simpler Office 365 user ID for people in your organization: Install Office on your PC or Mac.

Watch a short video to learn more:

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Domain names represent the online identity of companies and individuals. A domain name is how people refer to your company’s online presence. A domain name is a unique name that you choose to represent your company. After you buy a domain name, it can’t be taken or used by other companies.

In Office 365 for business, you can use a custom domain name with your email address, public website, and other services, for example, to make it easier for customers to find your business or organization on the web. You might also be asked to add and verify a domain name if you're setting up a school or nonprofit account, to verify your organizations status.

You can buy a domain in Office 365 or from a domain registrar. If you buy a domain from Office 365, we set it up for you automatically. Or if you register a domain at GoDaddy, we provide fast, easy way for you to set up your domain with Office 365 (Watch a short video about it).

When you sign up for Office 365, we provide you with an initial domain similar to contoso.onmicrosoft.com so you can get started.

Do I have to use a domain with Office 365?

Not at all. For example, in these scenarios, you don't need to use a domain with the services:

  • You're signed up for an Office 365 subscription that just provides downloads for Office apps like Word and Excel.

  • You're signed up for an Office 365 subscription that doesn't support features, like email, that use a domain.

  • You just need to confirm to Office 365 that you qualify for a school or non profit subscription. You add and verify a domain, but you don't have to set up email and other services.

  • You're setting up a Yammer subscription or a nonprofit subscription.

  • You want to try out the service by using the initial onmicrosoft.com domain, or you want to keep using your onmicrosoft.com domain.

How can I use a domain name in Office 365?

You can use your domain name in Office 365 with your email, public website, and instant messaging address.

  • Email: Your domain name lets you customize your email, so you can use a shorter, easier-to-remember address than the initial onmicrosoft.com email address that comes with your account. So instead of joe@contoso.onmicrosoft.com, the email address (which is also the work account that you use to sign in to Office 365) could be joe@contoso.com.

    When you change your email to Office 365, by updating your domain's MX record in the setup wizard, ALL email sent to that domain will start coming to Office 365. If other people use your domain for email, you must set up Office 365 mailboxes for each of those people. Otherwise they'll lose any email sent to them at your domain when you switch email for the domain over to Office 365. (Confusing? Learn more about how domains work with email.)

    Do you just want to switch a few email addresses to Office 365? You can take steps to pilot Office 365 with just a few email addresses instead.

  • Instant messaging: Your Skype for Business Online address can also be customized to use your domain name, so people in your organization can connect with each other on Skype for Business Online by using a shorter, easier-to-remember address (like joe@contoso.com).

Be aware that one thing in Office 365 that you can't use your custom domain name with is your team site or internal SharePoint Online site collections.

How can I learn more?

Get help with using domains in Office 365 or check out one of the following:

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