How to Perform Office 365 Tenant to Tenant Migration?

How to Perform Office 365 Tenant to Tenant Migration?

The number of Office 365 adoptions among organizations is rapidly increasing by the day. Often, organizations have to deal with multiple Office 365 accounts in situations like mergers and acquisitions. In other scenarios, there might be a requirement to consolidate tenants on different versions within the same organization to reduce the costs and complexity of daily operations. In this article, we will explain how the Office 365 tenant-to-tenant migration works and briefly discuss the steps that organizations must undertake when migrating their Office 365 from one tenant to another.

Snapshot of Microsoft/ Office 365 Tenant to Tenant Migration

The Office 365 migration from tenant to tenant requires planning at least two weeks ahead of the intended date. Here is a snapshot of the process which we will elaborate on in the following sections:

  • Prepare source and target tenants
  • Create a CSV file of user accounts
  • Create users in destination tenants
  • Start the tenant-to-tenant migration in Office 365
  • Prepare the domain whose user accounts are being migrated
  • Remove the Domain from the source and add the domain to the destination
  • Stop mail flow to the source tenant and add new DNS records to destination tenants
  • Do the final sync Once DNS records are updated.
  • Cleanup after completion of the migration project

Steps for Performing Tenant to Tenant Migration in Office 365

Follow the given procedure to migrate from one tenant to another tenant in Office 365.

  • Assessment and Pre-Migration Planning

    The first step of any Office 365 migration, including tenant to tenant migration, is to plan the migration process well in advance, in most cases, at least two weeks before the scheduled date, to avoid unforeseen disruptions. Planning the process includes taking measures to ensure that the prerequisites for the Office 365 migration are fulfilled and any other licenses for third-party migration tools have been acquired.

  • Preparing the Target Tenants

    The next step is to prepare the target tenant to migrate mailboxes from the source tenant. This might include creating an additional room in it to accommodate new user mailboxes. The migration process needs admin accounts for both the source and target tenants. Objects like Rooms, Resources, Groups, and Users from the source tenant will have to be created in the Target Tenant through Azure Active Directory consolidation or manually from the Microsoft 365 admin center.

  • User Accounts Preparation

    The IT team of the organization must generate a CSV file of the email addresses that have to be migrated to the target mailbox for using a third-party migration tool. It is advisable to to the source tenants’ email addresses.

  • Moving Objects to the New Accounts

    The Office 365 tenant to tenant migration is complete when all objects including calendars and contacts have been moved to the new accounts. There are different methods of migration, namely staged migration, cutover migration, and hybrid migration which have been discussed in another blog. Use the appropriate method depending on the number of Office 365 tenants and the Exchange Server.

  • Preparing the Domain

    The source Office 365 tenant will have to be merged with the target tenant. This is done by adding the source tenant to the target tenant’s Microsoft 365 admin center and creating TXT records for DNS verification. This will allow sufficient time for DNS records to propagate to the new server.

  • Office 365 Tenant to Tenant Migration Day Activities

    If you have planned your Office 365 tenant to tenant migration well, there aren’t too many activities to be performed on the day of the migration. Broadly, there are only four things to be done.

    • Stop receiving incoming emails to the source tenant.
    • Configure the source tenant domain to move to the target tenant.
    • Verify the source tenant’s domain on the target domain.
    • Select the best migration method and proceed with Office 365 tenant to tenant migration.
  • Stopping Inbound Emails

    The migrating server must deliver a “not reachable” message to mail servers that are trying to deliver new mail to it. It is advisable to rope in a third-party service that can queue emails for a pre-decided time during the transition period to prevent a non-delivery report from being sent to the senders.

  • Updating Mail Exchanger (MX) Records

    The MX records indicate the address of the mail server which receives emails for the Office 365 tenants. When the source tenant migrates to the target tenant, the server address receiving email on behalf of users will have to be changed to the target tenant’s address. Changing the address to which the records point will take time during which period there would be a disruption in the mail flow. This period, called time to live (TTL) has to be kept to the least possible value for minimizing disruption. So, the IT team must run tests to determine the TTL before proceeding with the migration.

  • Disabling Azure Active Directory Syncing

    The Azure Active Directory, which allows access to public folders, apps like SharePoint Online, and other resources must be forced to stop syncing before accounts can migrate from one Office 365 tenant to another. This process can take almost a day and has to be initiated early on. Any new changes in the source tenant will not be reflected once the sync is disabled. Hence, it must be planned accordingly, preferably on a non-working day.

  • Source Tenant Domain Preparations

    The source tenant domain has to be removed from Office 365 for the migration to succeed. This entails resetting SharePoint Online public websites, email addresses, and other objects back to the initial domain. Secondary emails will have to be removed and licenses have to be revoked before migrating to the new Office 365 accounts. The processes which are blocking the removal will have to be manually stopped using the PowerShell command.

  • Target Tenant Reception Preparation

    Once the source tenant domain has been added to the target domain, the transfer has to be verified in the latter’s admin center. The Azure Directory has to be configured for the new domain in the target domain and the licenses to be assigned to users for mailbox activation. Assign the old email addresses as the primary addresses and set passwords for them. The inboxes will start receiving mail once the MX record updates are complete.

  • Post-Migration Steps

    Outlook caches the list of addresses to which users send emails. After migrations, there is a possibility that the replies on migrated emails may not be delivered successfully. This issue can be resolved by clearing the Outlook Auto-Complete List.

What Are the Different Architecture Approaches for Microsoft Tenant to Tenant Migration?

There are several approaches for Microsoft 365 tenant-to-tenant migration, each catering to specific business scenarios and migration requirements. Here are those common approaches:

  • Single Event Migration: The single event migration involves moving all users and data from the source tenant to the target tenant in a single operation. This means that all mailboxes, files, SharePoint sites, and other data are migrated at once, and users are switched from the source to the target tenant on a specific planned date and time.
  • Phased Migration: It involves moving users, services, and data from one tenant to another tenant in a gradual manner. This method aims to minimize risks and disruptions during the migration process by spreading it over an extended timeline. Instead of transferring the entire source domain to the target domain at once, the migration is carried out in phases, allowing users to adapt to the changes more smoothly.
  • Tenant Move or Split: It is a migration approach used in scenarios where organizations need to move their entire tenant including user accounts, services, and data from one domain to another domain. However, unlike single-event migration, this method does not involve migrating accounts to a new on-premises Active Directory Domain Services (AD DS) forest.

What Are the Challenges in Office 365 Tenant to Tenant Migration?

Office 365 tenant-to-tenant migration comes with various challenges, which can make the process complex and time-consuming. Some of the common challenges include:

  • Data Migration Complexity: Transferring large amounts of data, including emails, files, SharePoint sites, and OneDrive content, while maintaining data integrity and metadata can be complex and time-consuming.
  • Compliance and security concerns: Ensuring data security and compliance during the migration process is essential, especially when dealing with sensitive information and regulatory requirements.
  • Licensing and subscription management: Transferring licenses and managing subscriptions between tenants can be complex, especially if different subscription plans are involved.
  • Data loss and data mapping: There is a risk of data loss during the migration if the process is disrupted due to power cut-offs or network issues. Additionally, mapping data from one schema to another in the target tenant requires careful consideration.
  • Third-party applications and integrations: Migrating data and services connected to third-party applications can pose compatibility issues, requiring additional configuration and adjustments.

Apps4Rent Can Help to Migrate from One Office 365 Tenant to Another

For Microsoft 365 tenant-to-tenant migration, thorough planning, and execution are essential to ensure a smooth transition of your organization’s data, applications, and services. Even the most competent IT teams with the best tools available may encounter challenges that require expert assistance to find optimal solutions. That is where Apps4Rent comes in.

As a Microsoft Solutions Partner, Apps4Rent has more than 16 years of experience in migrating emails, calendars, task management files, contacts, and several types of files from other sources to Office 365 and can help businesses in Office 365 tenant to tenant migration process without any data loss by using tested tools and methodologies. Our certified Microsoft experts are available 24/7 via phone, chat, and email to help you.

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