Windows Domain Migration

Migrating user mailboxes from one Office 365 domain to another Office 365 originates in scenarios where organizations merged with others or acquired by others. Considering a case where one company decides to take over another. All their assets will move to the new organization which has acquired the other.

Remember, moving users, mailboxes from one domain to another Office 365 is not an easy task, we have to plan the migration and follow all the required steps to do this task.

So, in this post, we are going to describe the method to move the user from one domain to another Office 365 in a detailed way.

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How to Migrate User Mailbox from One Domain to Another Office 365 –
Planning, Preparation & Migration

Before migrating the mailbox from Office 365 domain to another Office 365 we have to make a proper plan and prepare both source & destination Office 365 tenants. Planning is must require because there are many risks involved in this migration.

We must understand the time involved in completing the process and the challenges involved. Communication and email services may be down for employees for days. As a result, the business may get affected. Basically, this migration is divided into three primary phases –

1 – Planning
2 – Migration
3 – Post Migration

Step 1 – Planning

Proper planning needs to be undertaken before deciding to move domain from one office 365 account to another. Certain necessary steps need to be undergone and followed in a precise manner to migrate mailbox from Office 365 domain to another Office 365. Internet connectivity must be strong and consistent. Having finalized the move, follow the steps below.

  • Firstly, acquire additional Office 365 licenses to include the additional employees being added to the organization.
  • Also, make sure to have administrative privileges on both Exchange Admin Console of the source and the target account.
  • Alternatively, add a CSV file with names of all new accounts and passwords. And then, upload this file to Exchange Admin Console of the company that acquired the other.
  • Now, check that the new domain is created for the new employees. Now the new employees will have accounts for both the new and the old organization.
  • Before moving ahead, plan properly by creating a CSV of all the mailboxes to be moved.
  • Also, change the Time to Live (TTL) in DNS of the primary domain to a smaller number. One can go as low as up to five minutes.
  • In the final step, go to the Exchange admin center of the old company and disable directory sync.
  • Finally, notify the new employees about the details of the transfer process and the downtime involved

Step 2 – Migration

As we know there are no manual methods available to move users from one domain to another Office 365, therefore we have to use an automated Office 365 to Office 365 migration tool. By using the tool you can easily migrate emails, contacts, calendars, documents. This tool is feature-rich it provides multiple features which will help you to simplify complications to this migration. Some highlighted features of this tool are given below –

1: Migrate emails, contacts, calendars, and documents from Office 365 domain to another.
2: Date-based filter option to migrate the selected data.
3: User mapping option to create a mapping between source & destination Office 365.
4: Delta migration facility to move newly arrived data.
5: Facility to set account-based priority to the account to migrate first.
6: Support batch migration of multiple user’s mailboxes from one domain to another Office 365.    
7: Admin credentials of source & destination Office 365 are required to accomplished migration.

Step 3: Post Migration Steps

There are a few more things to be considered after the migration process has been successfully completed. Following steps needs to be performed in order to ensure a complete migration.

  • At first, each added employee needs to be given their new email address and password. This will help them to log in to their new mailbox in the new company.
  • Finally, guide each employee on ways to login to the Outlook Web App to access their old mailbox.

Final Words

Acquisitions can be a major transition for many companies. To ensure that employees transfer to new organization smoothly is the main concern of the employers. Most important is that the work must continue without much concern. Business must resume in the same manner as it was before the acquisition. There should be a smooth transition of employees and their accounts. Administrators have to make sure that proper planning is given to move the user from one domain to another Office 365.

Instructions on how to migrate users mailbox from one Office 365 domain to another Office 365 have been described in this article. Refer to it as a bible to make sure there is an efficient transfer of employee accounts and mailboxes takes place so that the organization can easily move the user from one domain to another office 365.


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