How to Set Up Exchange Online Mailboxes with a Custom Domain
Question details
A business needs to configure Exchange Online mailboxes using a custom registered domain (e.g., GoDaddy) instead of the default .onmicrosoft.com address for multiple users sharing one tenant.
- Product
- Exchange Online
- Device & OS
- not provided
- Scenario
- Setting up professional business email addresses for a new company using an existing custom domain.
- Observed behavior
- Users want to replace the initial fallback .onmicrosoft.com domain with a verified custom domain and ensure that multiple employees can be managed and licensed under a single Microsoft 365 tenant.
Ensure you have global admin access to your Microsoft 365 admin center and the login credentials for your custom domain's DNS provider (such as GoDaddy).
Add a Custom Domain and Assign Mailboxes
Connect your custom GoDaddy domain to Microsoft 365, verify it, and assign it to users within the same tenant.
The .onmicrosoft.com domain acts as an initial fallback domain for your Microsoft 365 tenant. By adding your custom domain, you can route all incoming and outgoing emails through professional, branded email addresses while keeping all users under one unified tenant.
Navigate to the Microsoft 365 admin center (admin.microsoft.com) and log in using your administrator credentials.
Go to 'Settings' > 'Domains' in the left navigation menu. Click on 'Add domain' and type in your GoDaddy-registered domain name.
Follow the setup wizard. If your domain is with GoDaddy, you will be prompted to sign in to GoDaddy to automatically authorize the DNS record updates. Alternatively, you can add the TXT record manually in your DNS settings.
Once the domain is verified, navigate to 'Users' > 'Active users' and click 'Add a user'. Fill in the profile details for your business partner or employee.
In the email address field for the new user, select your newly verified custom domain from the drop-down menu. Assign them an Exchange Online or Microsoft 365 license, then save the changes.
Contact Microsoft Support for Account Assistance
If you encounter issues assigning licenses or accessing subscription details, reach out to Microsoft Support.
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While setting up business emails with Exchange Online, your new company will also need reliable office software. WPS Office is a free, lightweight, and highly compatible alternative to Microsoft Office, perfect for teams looking to optimize costs without sacrificing functionality.
- 1. Download WPS Office: Visit the official WPS website and download the free installer for your operating system.
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Frequently Asked Questions
Can multiple users share the same Microsoft 365 tenant?
Yes, multiple users can be added to a single Microsoft 365 tenant. You just need to purchase and assign an individual Exchange Online or Microsoft 365 license for each user you add in the admin center.
What happens to the .onmicrosoft.com address after adding a custom domain?
The .onmicrosoft.com domain remains the initial fallback routing domain for your tenant. It operates invisibly in the background for system routing, but your users will send and receive emails normally using your new custom domain.
Do I need to buy my domain directly through Microsoft?
No, you can use a custom domain registered with any third-party registrar, such as GoDaddy, Namecheap, or Cloudflare, by verifying domain ownership and updating your DNS records in the Microsoft 365 admin center.
How long does domain verification take in Exchange Online?
If you use GoDaddy's automated DNS setup through Microsoft 365, verification is usually instant. If you are updating DNS records manually, it can take anywhere from 10 minutes to 48 hours for the changes to propagate globally.
