How to migrate from Exchange 2013 to Microsoft 365 (Office 365) and why do it now?

[Update]: Exchange Server 2013 reached its end of life (EOL) on April 11, 2023. We’ve updated this article to reflect this change and show you what migration options you have now.

Server migration is a very stressful task. It involves moving business-critical data between different locations. Since the extended official support for Exchange 2013 ended on April 11, 2023, the number of companies which are looking into migration away from it might be on the rise. While there is more than one possible target server to migrate to, Exchange 2013 to Microsoft 365 migration seems to be one of the most popular scenarios. In this article, I’ll show you what the available methods are to migrate from Exchange 2013 and how to approach them.

But first, let’s take a look at the main reason behind a sudden increase in migrations from Exchange 2013.

Exchange 2013 end of life

The main reason for migrating away from Exchange 2013 is that it reached its end of support. A quick look at the calendar tells us that its prime time is long gone and a few months after its tenth birthday, on April 11, 2023, Microsoft stopped providing technical assistance, as well as bug and security fixes.

What does “end of life” mean?

The technical term for end of life is the end date of extended support. It doesn’t mean that the Exchange Server will suddenly stop working. No, the Extended Support End Date means that the Server is officially labeled as unsupported. In other words:

• You shouldn’t expect any new updates.
• Getting technical assistance might be a challenge.
• You enter the high-risk area.
• Since most organizations run away from Exchange 2013, it will be harder to get help even from technical communities and forums.
• For the same reason, slowly but surely, most vendors will stop supporting Exchange 2013. It means that your IT toolbox will become limited.

Truth be told, on some rare occasions, there were security updates to Exchange Servers whose lifecycle has ended. And there are still some companies that successfully operate on Exchange 2010 which officially “died” almost 4 years ago. This brings us to a popular question.

Do I have to migrate from Exchange 2013?

It depends. If you want to comply with a security-by-design model, value your risk assessment specialists and in general prefer to live with peace of mind – it’s better to migrate, and to do it sooner than later.

I’ve seen many opinions like this:

“What’s wrong with an old Exchange server? It’s only email!”

This might be the right time to comment on that. “Only email” is what most companies depend on. Not only in terms of communication, but also record management, notifications about crucial processes and brand management. If something bad happens to email, companies can lose deals and their prospects’ trust. Organizations are under phishing and other attacks every single day. Keeping an old IT infrastructure increases the number of attack vectors. You’re staying behind and just waiting for something bad to happen. If you still need additional, specific reasons why to migrate away from Exchange 2013, here’s a couple:

• Transport-based enforcement system – emails from “persistently vulnerable Exchange Servers” are currently blocked in hybrid environments. Learn more
• No way to migrate directly to Exchange Server Subscription Edition or vNext (I’ll elaborate in a second).

So, if you want to run away from this unsafe environment, you have a few options available.

Available migration options

There are different destinations you might be interested in migrating to:

Newer on-premises servers

Most organizations that haven’t migrated to the cloud yet, have one of these two main reasons: they either require full control over the company’s data or prefer the on-prem one-time-purchase licensing model (and don’t like the cloud licensing model based on a monthly or yearly subscription). If that is the case, current migration options are Exchange 2016 or Exchange 2019. Not ideal options, since Exchange 2016 and 2019 reached the end of their Mainstream Support and have the Extended Support End Date set to October 14, 2025. In case of Exchange 2019, you also need to remember that upgrade from 2013 is only possible up to the version with CU14 installed.

If you look for a newer on-premises Exchange options to move to, I’ve got bad news. Exchange Server CU15 (and newer if it becomes available) as well as the new Exchange Server Subscription Edition (vNext) do not support move from Exchange 2013. For more details, head over to this Exchange Team blog.

And this pessimistic conclusion brings us to the last and, as it seems, most reasonable migration option, which is…

Microsoft 365 (Office 365)

That’s the destination most companies are likely to choose now. Microsoft doesn’t hide the fact that most development efforts are focused on their cloud offering. Microsoft 365 and related products give you the most features and offer the easiest way to get a successful hybrid work model. It’s easy to make an organization available from any part of the world, while offering premium security with tools like Azure Purview or Conditional Access Policies.

How to migrate from Exchange 2013 to Microsoft 365?

You have different migration methods available if you want to move mailboxes to Exchange Online.

• Cutover migration – a classic approach to migration, and Exchange 2013 is the last on-premises Exchange version that supports this method. In short, it allows you to move all mailbox content in one hop. It cannot be performed if you have more than 2000 mailboxes, but as this Microsoft’s article suggests, “due to length of time it takes to create and migrate 2000 users, it is more reasonable to migrate 150 users or fewer.”
• Hybrid migration – a hybrid migration means that you create and configure an environment with both on-premises Exchange server and Exchange Online (using the Hybrid Configuration Wizard) and move content from on-prem mailboxes to remote mailboxes in the cloud. While this gives you more freedom in staging the migration, it makes your IT infrastructure a bit more complicated. In short, you manage mailboxes on-premises, but all the changes are synced to the cloud using Microsoft Entra Connect (Azure AD Connect). Most people don’t entirely understand how hybrid environments work.
  Although Exchange 2013 allows you to configure a hybrid environment, it might be an idea worth reconsidering. Creating an Exchange 2013 and Exchange Online hybrid beyond the server’s end of life leaves you with a considerable security risk.
• Express migration – also called Minimal Hybrid. It’s a hybrid migration minus directory synchronization. It is supposed to be the quickest native migration method available.
• Manual methods – usually include recreating your organization’s structure in the cloud and using PST files to migrate content. That means exporting PST files on the source server (you can make it much easier if you use PowerShell, as I described here) and importing them to the target environment. Due to a lot of heavy lifting, the fragility of PST files and multiple levels on which it can go wrong, it is not recommended. Still, if you have only a few mailboxes and a backup in place, this might just work.
• Third party tools – use different methods to make the move smoother, quicker and easier. They are especially useful when migrating big environments with hundreds or thousands of mailboxes. CodeTwo Office 365 Migration is an example of such a tool.

Decommissioning Exchange Server 2013

Decommissioning old Exchange is one of the cleanup tasks you need to do after a successful migration. There’s a great article from Microsoft Exchange Team that explains how to get rid of Exchange 2013:

Decommissioning Exchange Server 2013

Why use a third-party tool for migration?

You don’t need to use a third-party tool to migrate from Exchange 2013 to Microsoft 365. However, using migration software, like CodeTwo Office 365 Migration, is the easiest way to go full cloud with the least effort. Migration is a challenging task, that’s why more and more administrators seek help in taking the burden off their shoulders.

With CodeTwo Office 365 Migration, you get:

• A step-by-step migration plan, which covers all migration aspects.
• The possibility to migrate primary mailboxes together with archive ones, as well as public folders.
• The option to automatically create and license mailboxes on the target server.
• Advanced control over the migration process, so you can, for example, migrate only the newest mailbox items, make the switch to the new environment, and then migrate all remaining items.
• Scheduling capabilities which allow you, for example, to plan a migration during the least busy hours.
• Advanced reports and notifications.
• Technical support from technicians who have helped multiple companies move their workload to the cloud.
• And more.

If you want to learn more about Office 365 migrations, you can download a free copy of Conversational Microsoft 365 Migrations by J. Peter Bruzzese.