Things you need to know for office 365 migration

Companies undergoing mergers, acquisitions, and divestitures often need to migrate the data between Office 365(Microsoft 365) tenants. This process becomes easy when you keep some points with you before starting the migration.

Reasons to migrate from one Office 365 tenant to another

Microsoft Office 365 is one of the best email platforms and a mature tool globally. Most of the businesses switching to this for a long time. Companies merge or acquire with other companies or divest of business units set up independently. This resulting more and more Office 365 to Office 365 migration projects.

For an instance, a company using Office 365 as their email platform acquires another company, where even there are also using Office 365 as their email platform. Now they want to integrate all the IT systems under one domain. This requires migration of users, data and domains into their tenant.

Complexities of Office 365 to Office 365 tenant migrations

Office 365 to Office 365 tenant migration feels harder than an on-premise to Office 365 migration as migrating domain(s) can only exist in one Office 365 tenant at a time. Microsoft allows a domain to reside in one tenant at a time

Suppose you are currently using in Office 365 tenant A, and want to migrate this domain, mailboxes, and users into Office 365 tenant B. You need to delete or rename user accounts, mailboxes, Office 365 Groups etc prior to adding the domain to tenant B. Once you rename the objects then remove the domain from tenant A.

Move the users of tenant A to another domain.

  • Go to the admin center.
  • Select Users > Active users.
  • Select the mailboxes next to the user names of all the users you wish to migrate.
  • Click More options (…) at the top section, and then select the Change domains.
  • In Change domains pane, select a different domain like

You’ll need to do this for yourself if you’re on the domain admin you want to remove. When you modify the domain for your account, you’ll have to log out and log-in to the new domain you chose to continue.

Now you can remove the domain for Tenant A.

Wait for the Office 365 platform to recognize the domain A isn’t associated with any tenant. Only then you can register it on tenant B and create mailbox on that domain.

For the migration of  domains, mailboxes, and users use EdbMails Office 365 migration which allows you to create the users and mailboxes in the target tenant using place holder names (i.e. not using the migrating domain), and migrates mailbox content.

Once the mailboxes ( exist in the target tenant B, they receive new inbound mails. When the domain was being removed from the source tenant and added to the target tenant, there was no mailbox in Office 365, and so no new mails will be delivered, and the sender will receive a Non-Delivery Receipt (NDR) from Office 365. This is about 1-3 hours.

It can be solved by email routing with another solution like Mimecast. Now the email is routed to Mimecast and then to Office 365, and before cutover Mimecast is set to queue the emails – so it receives and stores the inbound emails. There is no chance to lose of mails and non-delivery receipts are not being sent. The queued mail will be released and added into the mailbox once the domain is added to the target tenant. Also new mails will be updated in the new tenant.

What about other Office 365 data?

We have seen how to migrate the domain(s), mailboxes, and users in the above discussions, but let’s look in to other contents. Whether those (SharePoint, OneDrive etc.) contents can be migrated.

EdbMails helps to migrate these contents with specific license by maintaining the same structures in the destination tenant as that of source tenant. It maintains the data integrity during the migration. It supports incremental migration for the consecutive migration on the same system.

Install the application on multiple computers for the OneDrive and SharePoint migration to complete the migration of these contents at the same time that the mail migration does. So that all the user data updated in the new Office 365 tenant.

What about the source Office 365 tenant?

Once the migration is done, and all your users work in the same Office 365 tenant, what do you do about the source Office 365?

You can keep the source tenant (that you have just migrated out of) for as long as you like by keeping the necessary Office 365 licensing in place. If you remove the Office 365 licenses, all the data will be removed within 30 days.

EdbMails for Office 365 tenant to tenant migration

EdbMails is one of the third party Office 365 migration solutions that help for seamless migration of mailboxes between Office 365 tenants. It directly migrates mailboxes to live Exchange and Hosted Exchange server from the source Office 365. It helps to export Office 365 mailbox to PST. EdbMails helps to migrate other Office 365 contents such as OneDrive, SharePoint, Office 365 Groups and Microsoft Teams etc with the corresponding license plan. Its intuitive user interface facilitates easy selection of the mailbox data, filtering the data, and mapping of the source and target mailboxes.


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