You can add your own custom domain name to Office 365 and use it to personalize user names, email addresses, and websites. Before you can use the custom domain, you have to prove that you own it by creating a special DNS record. After you set up the record, we’ll run a query to verify that the record exists, and you’ll be ready to go.

Common causes of problems with adding domains

  • Missing DNS records. Before you can use a domain with Office 365 you have to create a special DNS record that lets us verify that you are the domain owner. If you’re a Small Business customer and are redirecting DNS maintenance to Office 365, this record has to be created before you change your Name Server (NS) record.
  • Domain is already in use. A custom domain can’t be used by more than one Microsoft online service, and the same domain name can’t be used by more than one Office 365 organization. If you used your custom domain name with a service like Hotmail or with an Office 365 trial account, you have to remove the domain from that account before you can use it with your Office 365 subscription.
  • Records are still updating. You create your DNS records at a particular Name Server (usually managed by your domain registrar), which is then responsible for making sure other DNS servers on the Internet know where to find your domain. It can take some time for the records to propagate around the Internet, so please allow at least 15 minutes and up to 72 hours before we can resolve your verification record.
  • Your plan doesn’t support subdomains. Office 365 Small Business doesn’t support subdomains. This means you can add contoso.com to your organization as a custom domain, but you can’t add sales.contoso.com.

Troubleshoot and resolve issues

I can’t add or verify my domain

Before you start, make sure you’re ready:

  • You have purchased a domain name from a domain registrar. Learn how to buy a domain name.
  • The domain you are adding has a valid Internet domain suffix. Not sure? Learn more here.
  • You know how to add DNS records, or who to contact to add DNS records. Not sure? Learn how to track down this information.
  • The domain name isn’t already in use with a Microsoft online service. If you’re using it with another Office 365 subscription, for example, remove the domain from that subscription first.

Ready? Follow these steps:

  1. Go to the admin portal and sign in as an admin.
  2. Click domains > add a domain. Follow the steps in the wizard to specify your domain name, get instructions for creating the DNS record at your registrar, and verify the domain.

I have a domain, but I don’t know where it’s hosted

If you know that your organization already owns a domain, but you’re not the person who set it up, follow the steps in this article to find your domain registrar or DNS hosting provider.

I don’t know how to set up the domain verification record

Follow the steps in I can’t add or verify my domain and get the instructions for your registrar. The record that you have to add is shown in the admin portal. You have two choices: create a TXT record or create an MX record. Some registrars don’t support TXT records, so you’ll create the MX record instead. These records are used only to prove that you own the domain and don’t redirect your mail or any other services.

Other resources

Diagnostic tools

  • OnRamp: Works best for organizations with an existing on-premises organization that are moving to Office 365. Answer a few questions about how you want to set up your organization, and OnRamp runs automatic checks against your environment to verify the readiness of your on-premises organization. View the results in the domains category to identify possible issues with your existing domains.
  • Microsoft Remote Connectivity Analyzer: Use the tests available with this tool to check the external DNS records for your domain.