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Office 365 Migration Keeping the Same Domain Name

Office 365 to Office 365 migrations with the same domain name differ from standard migrations because Microsoft only allows a domain to reside in one tenant at a time. To perform a same-domain migration, user addresses on both the source and destination tenants must be switched to 'onmicrosoft.com' domain names instead of the vanity domain names. Adding the domain to the destination tenant will cause brief downtime for this reason.

Some email downtime is unavoidable during this process, which occurs in the window between removing the domain from the source tenant and adding it to the destination tenant.

Office 365 to Office 365 Migration with same domain

Reason for moving the Office 365 tenants with same domain
- You may need to move away from Office 365 providers like GoDaddy, Rackspace, or Comcast to manage the tenant directly under Microsoft.
- To reduce email latency, you may want to shift your Office 365 servers from Germany to the USA, from China to the USA, or the reverse.
- During business acquisitions and mergers, companies often need to consolidate into a different Office 365 tenant while retaining the existing domain name.
- Migrating with the same domain means users keep their current email addresses, which eliminates confusion and minimizes disruption to day-to-day operations.
- Retaining the domain also preserves brand consistency, email addresses and website URLs stay the same for customers, suppliers, and partners.
- A domain name change also introduces deliverability risks. Emails sent from a new domain are more likely to be flagged as spam or blocked outright. Keeping the same domain sidesteps those issues entirely.
Steps involved before migrating Office 365 in the same domain
Step 1: Move the users of source Office 365 to another domain
- Open the Microsoft 365 Admin Center.
- Select ‘Users’ > ‘Active users’.
- Choose the users you want to move by selecting their corresponding checkboxes.
- Select ‘More options (…)’, at the top of the page, and then choose ‘Change domains’.
- In the Change domains section, switch your current domain to something like xxx.onmicrosoft.com.
If your admin account is also using the domain you plan to remove, update your account’s domain as well. After making the change, you’ll be signed out and must log back in using the newly assigned domain.
Step 2: Remove the domain from source Office 365 server
- In the admin center, go to ‘Settings’ > ‘Domains page’
- On the Domains page, select the domain that you want to remove
- In the toolbar pane, select ‘Remove domain’
- Follow any additional prompts, and then select Close
Note: Removing a domain from Office 365 can take as little as 5 minutes when it has few references, security groups, distribution lists, users, and Office 365 groups. If the domain appears across many of these objects, the removal process can stretch to several hours or, in some cases, an entire day.
After the domain removal is complete, users will not be able to access their email, unless they know their tenant name and log in with their tenantname.onmicrosoft.com email addresses.
Step 3: Prepare administrator account on source tenant for migration
- In the Office 365 admin portal, change the UPN of the admin account to the onmicrosoft.com address.
- Create an administrator account (Global admin) in Office 365 to be used for migration.
- Test the mailbox and email access by logging into the tenant
Note: Test the access to the tenantname.onmicrosoft.com addresses, not to the domainname.com addresses. Make sure that the tenantname.onmicrosoft.com account is attached to each mailbox in Office 365. By default, it should be attached.
Step 4: Verify the domain on destination Office 365 server
- Verify the domain in the Destination Office 365 account. We recommend the use of the wizard in Office 365 for this operation, because after the domain is verified with the Text record, it offers to change all the users to the new Default Domain.
Note: Since the domain was previously added to the account, all that needs to be done is to click the Verify button. If the domain is unable to be verified, and there is an error saying the domain already exists on another account, contact Microsoft and inform them that the domain needs to be manually deprovisioned.
- Create an administrator account in Office 365 to be used for migration
- Set up accounts on Office 365 and assign licenses. These can be created in several ways:
  - Manually create the mailboxes, one at a time.
  - By bulk import, via CSV file. Import the CSV file and create the mailboxes.
  - By DirSync, AAD Sync or AAD connect.
- Confirm that every user has the Destination ‘domain.com’ domain name added to their mailbox. Add manually if necessary.
- Prepare the tenant to send and receive large mail items in Office 365.
Step 5: Update your DNS records
MX Record update: On the DNS provider's portal, change the primary MX record to reflect the DNS settings for the new Office 365 organization. The DNS settings to change include Autodiscover, MX, and SPF records. Also, remove the old settings.
These settings can be found in the Office 365 admin portal,
- Inside Office 365, click Admin in the header.
- On the Admin page, click Domains in the left pane.
- Click the domain name to be set up, and then click DNS Settings.
- This page lists the DNS records necessary to set in order to use the Office 365 services. Steps to add DNS records to connect to your domain.
Step 6: Migrate your Source Office 365 to the target Office 365
Finally, migrate mailboxes from one tenant to another with EdbMails migration tool.

Frequently Asked Questions (FAQs)

Can I migrate Office 365 mailboxes to another tenant while keeping the same domain name?
Yes. EdbMails fully supports Office 365 tenant to tenant migration same domain name. You must temporarily switch users to the onmicrosoft.com domain on the source tenant, remove the domain, verify it on the new tenant, and then migrate using EdbMails.
Can I migrate shared mailboxes, public folders, and archive mailboxes between two Office 365 tenants?
Yes. EdbMails supports migration of Primary mailboxes, Shared mailboxes, Archive (In-Place Archive) mailboxes, Public folders.
What happens if the migration is interrupted during tenant transfer?
If your Office 365 tenant to tenant migration is interrupted due to network issues, throttling, or system shutdown, EdbMails automatically resumes the migration from the exact point of failure when you restart the process.
It does not duplicate or re-copy previously migrated items, because EdbMails uses a built-in incremental / delta migration engine that tracks what has already been migrated and only transfers the remaining data.
This ensures zero data loss, faster recovery after interruptions, and a smooth tenant transfer even in unstable network environments.

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In this manual

Introduction Reason for O365 tenants O365 migrating same domain