Connecting a domain to Microsoft Office 365 from a Third-Party Provider (manual setup)

If you purchased Microsoft Office 365 from a third-party provider, you can use a domain registered with IONOS for the Microsoft Office 365 email functions. To do so, you must add the domain in the Microsoft Office 365 Admin Center and prove to Microsoft that you are the domain owner by creating a TXT Record. You must then create the necessary MX, CNAME, SPF and SRV records to use Microsoft Office 365.

These steps are not necessary if you purchased Office 365 from IONOS. We do the domain configuration for you automatically in the background.


You cannot use your domain with both Microsoft Office 365 and Mail Basic or Mail Business simultaneously. Therefore, carry out the steps below only if you want to configure all mailboxes for a certain domain to be used with Microsoft Office 365.

The necessary steps are summarized below:

  • Authenticate the domain using a TXT record
  • Add an MX record for forwarding emails in the IONOS Domain Center
  • Create subdomains and configure CNAME records in the IONOS Domain Center
  • Save the necessary SPF record in the IONOS Domain Center
  • Save the SRV records needed to use Microsoft Teams in the IONOS Domain Center
  • Verify the necessary DNS settings in the Office 365 Admin Center

The final step is to check the DNS settings you made in the Office 365 Admin Center to make sure that you will be able to successfully use your domain with the Office 365 services after configuration is complete.

To do so, go to the bottom of the Update DNS settings page, click Verify, and then click Finish. You can now use your IONOS domain with Microsoft Office 365.