Cutover migration

In this article, you will learn about what the cutover migration is, how to perform it in CodeTwo Office 365 Migration, and what are the most common use cases for this migration type.

What is a cutover migration?

A cutover migration is the simplest migration type to implement. It assumes migrating all data (mailboxes, calendars, public folders, etc.) in one go. This migration type is recommended for small and medium-sized enterprises (SMEs) that want to quickly migrate to Exchange Online, with as little effort as possible. When configuring a migration job in CodeTwo Office 365 Migration for the cutover migration, you simply need to specify which mailboxes to migrate and leave all other options at their default settings – unless you decide not to migrate specific types of data. Keep in mind that if you are configuring an IMAP migration job, only emails can be migrated.

Since SMEs shouldn't have that much data, the migration process will probably take a couple of days. This is why the cutover migration is often run over the weekend, outside the company’s operating hours. This type of migration usually involves changing the MX records after the migration is completed, and often also transferring the domain to the target server. This is followed by running delta migration in CodeTwo Office 365 Migration to let the program search for any new items on the source server and migrate them to the target mailboxes. Once that's done, your employees can begin working in a new Exchange environment and access all their data.

How to perform the cutover migration in CodeTwo Office 365 Migration


Keep in mind that some steps described below may differ in the case of using a CSV file with matched source and target mailboxes to perform a migration (e.g. from a hosted Exchange server). Instructions on how to configure a migration job for this scenario can be found here.

Configuring a migration job for the cutover migration

  1. Click Create a new migration job on the Dashboard tab and select your source server (Exchange on-premises, Office 365, or IMAP server).
  2. Provide a unique name for the job.
  3. In the Mailbox types step, select if you want to migrate primary mailboxes, archive mailboxes or both.
  4. In the Source mailboxes step, click the Source server drop-down menu and select Add new source connection. Follow one of the links below to:

    If you have already configured a connection to your source server, simply select it from the drop-down menu.


    When you’re migrating from an IMAP server, you will not be able to continue the migration job at all once you change the domain on your source server.

  5. 5a. If you are connecting to the source Exchange on-premises server or Office 365 tenant, select which mailboxes you want to migrate. You can leave the default settings to migrate everything.
  6. 5b. If you are migrating from an IMAP server, you need to prepare a CSV file with information regarding all your mailboxes.
  7. In the Target mailboxes step, click the Target server drop-down menu and select Add new target connection. Follow these steps to configure your connection. If you have done that already, select your target server from the drop-down menu.
  8. In the Match mailboxes step, you need to pair the mailboxes from the source server with the ones on the target server. The program will attempt to do that automatically. Click Match mailboxes in the wizard. In the window that opens click Automatch > Automatch all mailboxes or select the mailboxes you want to match (you can choose them one by one by using the Ctrl button, use the Shift button for multiple selections), and click Automatch > Automatch selected mailboxes. If some mailboxes were not paired, you can adjust the matching parameters, or match them manually. If you didn’t create mailbox-enabled users on your target server prior to that step, the program can do it for you. Either way, once all mailboxes are matched, click Save and close the Match mailboxes window.
  9. You can click the Enable scheduler checkbox in the next step to let the program automatically start and stop the migration job. Learn more about setting up scheduler.
  10. Adjust the time and folder filters according to your needs. If you plan to migrate everything (excluding Spam/Junk folder), leave the default settings as they are.
  11. You don’t need to make any changes in the Advanced settings step unless necessary. Learn more here.
  12. Once you reach the Job summary step, verify the migration job settings and click Finish.

If you have enabled the scheduler, the migration job will start automatically, according to your settings. If not, to start the job, go to the Jobs tab, select your migration job and click Start on the menu.

Post-migration activities

If applicable, once the migration is finished, you need to transfer your domain to the target server and/or change the MX records via your domain host to enable mail flow to the new server. Remember that even when you do so, until these changes propagate, you can still receive emails on your old server. Therefore, first make sure that the MX records are updated, and then perform the following steps in CodeTwo Office 365 Migration:

  1. Reconfigure the source and/or target connections if you have changed the domain in either of them.
  2. Go to the Jobs tab and select your migration job.
  3. Select all mailboxes (press Ctrl+A), and click Refresh email addresses on the menu.


    The refresh functionality is not available when you’re migrating from an IMAP server.

  4. Check the results window. In case of any errors, refer to this article for more information.
  5. Once all email addresses have been refreshed, click Run delta migration from the menu. This will migrate any new emails that were sent to your old server during the migration or when the changes to the MX records were propagating.
  6. If after the migration Outlook doesn't connect to the new Office 365 tenant, you also need to create a new Outlook profile and set it as the default one for each mailbox user. You can achieve these two goals in an automated way by using a GPO (see this article) or Microsoft Intune (see this article).

This concludes the post-migration actions. You can now remove the migration job from the program by clicking the Delete button on the menu.

Cases for using the cutover migration

  1. Efficient migration to Office 365
  2. Small business expansion
  3. Changing the company’s business area
  4. Long cutover – effortless migration
  5. Migrating to Office 365 after the acquisition

Efficient migration to Office 365

A small company plans to migrate to Office 365 from an old on-premises Exchange server. After taking the amount of data to be migrated into consideration, it has been decided that the whole process should take place during the weekend. Since all data will be migrated, no time or folder filer will be set in CodeTwo Office 365 Migration. However, it would be a good idea to configure the scheduler, so that the program can start the migration job automatically, outside the company’s operating hours. Once the migration is finished, the domain in the target Office 365 tenant needs to be updated. All that’s left is to refresh email addresses and use the Run delta migration feature to migrate any new items that might have been created on the old server during the migration.

Small business expansion

As part of your business expansion plan, you intend to employ more workers and implement newer technologies. You also want to migrate all your emails from an IMAP server to Exchange Online. You plan to leave the migration for the night, as there are not many mailboxes to be transferred. However, you may need to include daily throttling limits, if they apply on your IMAP server. For example, Gmail has a download limit of 2500 MB per mailbox per day. Since your Exchange server is already set up and running, and you didn't have your own domain earlier, no domain change is necessary. After the migration, when your employees begin their work the next day, you just need to provide them with login details to their new mailboxes. Just make sure use the Run delta migration feature once in a while in CodeTwo migration software to migrate new messages that were sent to the old email addresses or simply configure forwarding on your old IMAP server to your new server.

Changing the company’s business area

The cutover migration is also a good solution when you want to drop one business and pick up another. Let’s consider a case where you have changed your business area, together with the name of the company. You even decided to leave the old on-premises Exchange server and move to Office 365. The analysis of all emails showed that only the latest data, not older than 6 months, should be migrated. And only emails, contacts, and calendars. You need to configure the migration job wizard to exclude unnecessary folder types, such as notes, tasks, and journals, as well as items older than 6 months. Since you will be running your business under a new name, you have probably also bought a new domain – this means that no MX records change is needed. Therefore, once the migration is completed, there is nothing else to do in the CodeTwo program.

Long cutover – effortless migration

The cutover migration can also be applied when you have a lot of data to be migrated. This use case assumes that your employees keep working on an old Exchange server until everything is migrated. It also involves configuring as few settings as possible. You simply need to select all mailboxes (including public folders, if applicable), match them with their counterparts on the target server and run the job. You can skip the configuration of scheduler and filters. The migration job will run 24/7, even during the operating hours of your company. Once finished, now outside the working hours of your company, change the MX records (and transfer the domain to the target server, if necessary), use the Refresh email addresses option in CodeTwo Office 365 Migration, and use the Run delta migration option to migrate what’s left on your source server. Once that’s done, your employees can start using their new accounts.

Migrating to Office 365 after the acquisition

This use case refers to a situation where two companies are merged or one acquires another. Usually, in such cases, the data is only transferred from one company to another. Both companies use Exchange Online, but there’s no need to keep both tenants. It has been decided that during the transition period, the migrated mailboxes will be using the old domain, so as not to confuse the customers. The migration will be performed outside the operating hours of both companies. All data is migrated and no time filter is applied, so what’s left to do is to configure the scheduler accordingly. Once the migration is completed, you need to switch to the default domain on the source server, and to the domain for the newly created mailboxes on the target server. Finally, refresh email addresses in the program and use the Run delta migration feature to check if there aren’t any emails left on the source server.

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