How to Migrate Exchange Server Mailboxes to Office 365 (Exchange Online)?

Summary: In this post, we’ve discussed different methods to migrate Exchange server mailboxes to Office 365. You can choose the suitable method, depending on the complexity of Exchange setup and the volume of mailboxes. In addition, we’ve mentioned an automated way for quickly and easily migrating Exchange mailboxes directly to Office 365.

When Microsoft officially launched Office 365 – its cloud-based emailing platform in 2011, a majority of organizations and businesses that used to operate with on-premise Exchange server have started shifting to Office 365. There are various reasons that prompt businesses and organizations to migrate from on-premise Exchange server to Office 365 (Exchange Online). Though organizations have universal control over the hardware and full control of all Exchange data in on premise setup, it requires regular efforts with regard to maintenance and security of the Exchange server. This would often need additional cost, resources, and human-hours.

On the other hand, Office 365, being a cloud-based platform, provides more scalability and flexibility without the need of investing on the infrastructure. The other major benefit of moving to Office 365 from Exchange server is that it offers easy and secure remote work.

Now the question comes up is ‘how to migrate Exchange server mailboxes to Office 365’. There are different methods to migrate mailboxes from on-premise Exchange to Office 365, depending on the complexity of Exchange infrastructure and the volume of mailboxes and their storage.

Methods to Migrate Exchange Server Mailboxes to Office 365

Here are some methods to migrate mailboxes from on-premise Exchange server to Office 365 (Exchange Online):

Method 1: Cutover Migration

In this method, the migration happens at once, with Exchange server being decommissioned and users begin working on the new setup. Cutover migration allows you to migrate all the mailboxes from on-premise Exchange server to Office 365. You can migrate up to 2000 mailboxes at once by using this method. However, it’s suggested to move not more than 150 mailboxes at a time as the process can take considerable time in creating and migrating a batch of 2000 mailboxes.

If you want to immediately migrate the entire Exchange environment to Office 365, this method is ideal for you. Cutover migration can be performed by using the Exchange Admin Center (EAC). This method supports Exchange server 2003, 2007, 2010, and 2013.

Method 2: Staged Migration

In this method, migration and synchronizing of the data are done in stages. Staged migration is ideal for organizations and businesses who cannot afford huge maintenance window and want to create a permanent mail coexistence with Exchange server and Office 365.

Staged migration allows you to migrate more than 2000 mailboxes. This method involves synchronization of accounts between Exchange server Active Directory (AD) and Exchange Online. In addition, Exchange users are required to create new profile in Office 365. Staged migration works only for migrating mailboxes from Exchange 2003 and 2007 to Office 365.

Method 3: Hybrid Migration

Hybrid migration allows you to easily migrate the mailboxes from on-premise Exchange server to Exchange Online. In this method, there is no need for an individual to create a new mailbox and import information. This method is suitable for those who want to maintain both on-premise email servers and cloud-based mailboxes while migrating the users to Exchange Online. This methods support migration from Exchange server 2010 and above versions. There are three types of hybrid migration – minimal hybrid migration, full hybrid migration, and express hybrid migration.

Similar to staged migration, this method requires you to synchronize Active Directory with Office 365 to move mailboxes of the users to cloud. If in case you’re not able to implement directory synchronization, you need to use a third-party migration tool.

Method 4: IMAP Migration

Internet Message Access Protocol (IMAP) is used for migrating users’ emails from the IMAP-enabled email clients such as Gmail, Yahoo, Hotmail, Exchange, etc. to Office 365. In this migration method, you can migrate only inbox items and other email folders. You can’t move other mailbox items such as contacts, tasks, calendar, notes, etc. It is to be noted that users must be added to Office 365 before using the IMAP migration.

Method 5: Migrate Mailboxes to PST

In this method, you need to first export the Exchange server mailboxes to PST and then import the PST to Office 365. For Exchange server 2007 or older versions, you can export mailboxes to PST by using export-mailbox cmdlet or ExMerge utility. For Exchange 2010 and later versions, use PowerShell command – New-MailboxExportRequest to export mailboxes to PST.

 A Simple and Quick Way to Migrate Exchange Server Mailboxes to Office 365

Migrating Exchange server mailboxes to Office 365 by using manual methods requires technical know-how, expert supervision, and choosing the right method for an error-free migration process. In order to avoid all hassles and unnecessary efforts, you can use a specialized Exchange to Office 365 migration software such as Stellar Converter for EDB. The software makes the entire process of migrating mailboxes from on-premises Exchange server to exchange Online simpler, quicker and more convenient.

Stellar Converter for EDB is a DIY tool with easy-to-use interface and doesn’t require any technical proficiency and deep understanding. You can export the Exchange server mailboxes directly to Office 365 within a few clicks. The software can restore accidentally deleted offline mailboxes and also allows searching for specific emails in offline Exchange database. It supports migration from MS Exchange Server 2019, 2016, 2013, 2010, 2007, and lower versions.


To perform migration of mailboxes from Exchange server to Office 365 manually requires extensive planning in order to avoid errors and minimize the downtime. In addition, there are risks involved in using some manual migration methods such as chances of data loss, synchronization error, and other issues that may arise during migration process. Above all, these migration methods are complex, time-consuming and require a lot of efforts and resources to perform.

If you want quick and effortless migration of mailboxes from your on-premises Exchange server to Office 365, use Stellar Converter for EDB. The EDB to PST converter software can export both online and offline EDB files directly to Office 365 or live Exchange.

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