Cutover Migration – Migrate Exchange Mailboxes to Exchange Online

Migrations are never an easy task and trying to migrate to Microsoft 365 or Office 365 can be hard if the end user is not keen for some downtime or some hiccups along the way. If you have an older version of Exchange like 2010 or Microsoft SBS 2011 then you need to go for the cutover migration. If you have Exchange 2007 then you will need to use IMAP migration, which in itself has some limitations. First things first, one must take precautions and a good backup of the Active Directory along with the Exchange server is to be taken. We start by creating our Microsoft 365 or Office 365 tenant and verifying the domain so that we have a good start.

Before starting the cutover migration configuration, make sure that the server hosting the Exchange server has been updated with the latest updates and services packs. Running the Best Practises Analyser is not a requirement but it will help the process and solving unwanted issues or complications. Analyse the size of each mailbox and make sure they do not exceed the 15GB as to minimize the implications during upload or bandwidth degradation. I would suggest archiving the mailboxes to keep the last year in the mailbox. This will improve the migration process and reducing the chance of corruption or upload issues.

Benefits of Microsoft 365 Migration

Migrating to Office 365 offers several advantages in collaboration, security, and management, apart from the financial part. With collaboration we get Microsoft Team, Co-Authoring, OneDrive, SharePoint Online and other tools that can help us work better and more secure. The security layer in the Information Rights Management (IRM), Multi Factor Authentication (MFA), Enterprise Mobility & Security (EMS), amongst others. Adding to this there is the customization of subscriptions depending on the user needs, software standardization and scalability of the tenant.

Common Challenges and Solutions

There are several challenges before, during and after the migration. Such challenges include the setup of the licenses and what to migrate to the online platform. Sometimes the preparation work is not considered, and it could have issues on the project outcome, good preparation is key. There are other technical issues which Office 365 brings that are the data size limitations where again, preparation work needs to be done on checking public folder and mailboxes sizes to ensure that these are in line with the Office 365 limits and maybe enable archiving or split the data. Other considerations are the bandwidth that needs to be increased at the office since a lot of users are not using online services, maybe have a redundant connection, and also the user downtime, during the migration and post migration as this need to planned accordingly.

Best Practices for Exchange Server Preparation

Here are some of the best practices which then depending on the infrastructure and business needs.

• Taking stock of all the mailboxes and public folders to be migrated and those which will be disposed, including the size of the resources.
• Cleanup the local Exchange Server.
• Decide if all the data will be moved, or a cut-off is decided.
• Keeping an inventory of all the mailboxes along with the ideal subscription assignments.
• Updating the Exchange Server with the latest Cumulative Update and operating system updates including any needed Service Pack updates.
• Running the Best practices Analyzer.
• Planning the migration including possible downtime

Prepare the users for the new setup and offer training where needed.

Mailbox Size Considerations

Ater reviewing the mailboxes and public folders to move to Office 365, then we need to analyze and see the limitation depending on the subscription assigned to the user.

We need to take in consideration archiving from a particular year or the business would decide to not retain data before a particular year depending on the business, or legal obligations. 

Another option would be to ask the users to cleanup their mailboxes, we all know some of the users who keep everything despite there is archiving and backups.

Office 365 Cutover Migration Steps

• Sign in the Office 365 tenant as the Global Admin.
• Click on Setup and Domains to add your domain.
• After the DNS verification, you will be able to use the domain in the user’s email address field.
• From the Exchange admin center in the Microsoft 365 or Office 365 admin portal. Click on ‘Recipient’ and click on ‘Migration’. Click on the ‘More’ button and click on ‘Migration endpoints’.

• Click on the ‘+’ Sign to create the new endpoint and in the first screen tick ‘Outlook Anywhere’, Click Next.

• In the next screen, you will be prompted to enter the ’email address’ of one of the mailboxes to be imported and the domain account name and password of a user who has administrative privileges on the Exchange server.
• To confirm the endpoint you will need to enter the FQDN which is hosting the Exchange server and the RPC Proxy server which in most instances would be the same as the Exchange Server.
• Here is the tricky part, you must make sure that Outlook Anywhere is working successfully and without any issues.

• After the verification, you will have the Microsoft 365 or Office 365 connected to your Exchange Server. Now, on the Migration screen click on the ‘+’ sign and click on ‘Migrate to Exchange Online’.

After going through the rest of the wizard and entering the required details and credentials, the data will start to copy. After some time, you can go to the same screen and check the progress. If all goes well, you will get the status of the mailboxes as Synced and the initial synchronization is completed.

From this moment, you can cut over the DNS records and assign the licenses to your users. From the Active users, you can either assign the licenses one by one if you have mix of E3, Business Essentials or Premium or by using the bulk actions for the users.

• To change the DNS records, you must open the domains from the setup menu on the left sidebar.

You will be required to enter the additional DNS record with your DNS provider, which are given by the portal in the page. If you want, you can either choose to go with your own DNS provider of use the Microsoft 365 or Office 365 DNS facility which mind you, you still need a DNS provider for the first verification process of the domain, afterwards you can disable it and route the Name Servers (NS) to Microsoft 365 or Office 365 directly.

After adding the DNS entries please note that due to the global DNS propagation, the change to be reflected everywhere it can take up to 24 hours. This may cause some delivery issues during the period and some emails can be delayed but unfortunately, it’s part of the migration headaches.

From here onwards, you can say to the users that they can work on their new mailboxes using mobile and web access. For the local users you need to make sure that any DNS entries pointing to the internet domain are updated. After Exchange has been uninstalled from the server you must make sure that any Autodiscover entries are removed and a new CNAME records has been created which is pointing the Autodiscover. to Autodiscover.outlook.com like below. Also, you must be sure that there are no records which are left there from the uninstall which can cause issues with Autodiscover service, so make sure that you clean up your Active Directory Schema after the uninstall.

Once complete this can be tested by opening a command prompt and trying to ping the autodiscoverAutodiscover.. If it does not work or it is not pointing to the right IP, then run ipconfig /flushdns and retry.

Although it will say Request timed out, you must make sure that it resolved correct to the onmicrosoft domain.office.com. Once this is ready you may go ahead to setup your local Outlook to connect via Microsoft 365 or Office 365. Better said than done as if all goes well and your setup is impeccable, you will have a clean migration, but it can get tricky when it comes to those pesky issues that return misleading error message.

As said in my first paragraph you can say that the above will not work on your Exchange 2003 and below. For that, you would need to use the IMAP migration as contacts, calendar items or task will not be migrated and you would have to export and import these through Outlook. You can migrate up to 500,000 items per user mailbox and each email must not be larger than 35MB. Of course, with IMAP migration you would need either to know the password for the users’ mailboxes or reset them, which would create an impact on your users.

Post-Migration Cleanup and Validation

Once the migration is complete, one can go ahead with the post migration tasks. First, we need to ensure that one last backup was taken of the Exchange Server. The next thing is to remove all the mailboxes from the Exchange Server as well as the system mailboxes. After this step we can go ahead and uninstall the Exchange Server. Why is this needed? The configuration of all the Exchange Server is stored in the Active Directory Schema and there are a lot of changes in the schema which relate to Exchange Server. So, just shutting down the Exchange Server and decommissioning the Exchange Server would mean that these parameters are not cleaned which could lead to routing and other problems. After the above is complete, one can easily decommission the Operating system and server.

Conclusion

On the other hand, when going through migrations and post migration, the first thing that comes in mind is to have a low impact on your users and a low administration error from the sysadmin side. Adding to this, if a mailbox has been forgotten or one would need to retrieve historic emails from the decommissioned server, this would not be possible. One needs to also consider that exporting directly from an EDB file is not possible with the native tasks. Stellar Converter for EDB takes a few minutes to install and for its small size, the EDB to PST converter software is very powerful.

You can use this application for the actual migration to Office 365 of user mailboxes, shared mailboxes, user archives, disabled mailboxes, and public folder with ease and with a peace of mind, with automatic mailbox matching, parallel exports, and priority exports for your VIP users. Post-Migration, the application can also extract data from offline or online EDB files to PST and other file formats.

Was this article helpful?

YES0

NO

About The Author

Eric Simson

Eric Simson is an Email Platform Consultant and is associated with Stellar Data Recovery from last 6 years. He writes about the latest technology tips and provides custom solutions related to MS Outlook, MS Exchange Server, Office 365, and many other Email Clients & Servers.