Migrate Email Accounts to Microsoft 365 or Office 365?

In This Article

• Migrate mailboxes from Exchange Server
• Use the Import Service to migrate PST files
• Migrate email from another IMAP-enabled email system
• Have users import their own email
• Work with a partner to migrate email
• Users provisioning for the different migration types

Overview

If your organization needs to migrate email to Microsoft 365 or Office 365 from other systems, there are several strategies to choose from. Your admins can migrate mailboxes directly from Exchange Server or from any IMAP-enabled service. Meanwhile, individual users can transfer their own email, contacts, and additional mailbox data into a Microsoft 365 or Office 365 mailbox that’s set up for them. You can even collaborate with a trusted partner to handle your migration needs.

Before diving into any email migration, it’s essential to review limits and best practices for Exchange Online (link provided in the original documentation). Ensuring you understand these guidelines will help you achieve the performance and outcomes you want.

If you’re unsure which migration path suits your organization best, check out these resources:

• Decide on a migration path
• Exchange migration advisors

Tip: Another helpful resource is the FastTrack Center Benefit Overview, where FastTrack specialists can assist you in planning and carrying out your migration. For more details, see Data Migration. You can also check out an overview video (if available) for a quick visual understanding of the process.

Migrate Mailboxes from Exchange Server

If you have an existing on-premises Exchange Server environment, an administrator can migrate all mail, calendars, and contacts to Microsoft 365 or Office 365. This can be done using either a staged or a cutover migration. Whichever method you choose, each user’s mailbox—complete with email, calendar entries, and contacts—can be transferred.

There are three main approaches you can take when migrating mailboxes from an on-premises Exchange Server:

Cutover Migration (or Express Migration)

1. Ideal if you’re running Exchange 2003, 2007, 2010, or 2013, and have fewer than 2,000 mailboxes.
2. You can launch a cutover migration directly from the Exchange Admin Center (EAC). See Perform a cutover migration to Microsoft 365 or Office 365.
3. For steps on how to use Express migration, see Use express migration to migrate Exchange mailboxes to Microsoft 365 or Office 365.

Important :Although cutover migration supports up to 2,000 mailboxes, creating and migrating so many at once can be lengthy. In practice, you may want to limit cutover migration to 150 users or fewer for better efficiency.

Staged Migration

1. Recommended if you’re running Exchange 2003 or 2007 and have more than 2,000 mailboxes.
2. To learn the basics, visit What you need to know about a staged email migration to Microsoft 365 or Office 365.
3. For a step-by-step guide, see Perform a staged migration of Exchange Server 2003 and Exchange 2007 to Microsoft 365 or Office 365.

Hybrid Deployment and Migration

1. Perfect if you want to keep some mailboxes on-premises and gradually move others to the cloud.
2. Ideal for Exchange 2010 with 150–2,000 mailboxes, or if you’re running Exchange 2013 or later and prefer a phased approach.
3. For details, visit Use the Microsoft 365 and Office 365 mail migration advisor.

Use the Import Service to Migrate PST Files

If your organization manages lots of large PST files, the Import Service is a great option for getting email data into Microsoft 365 or Office 365. An administrator can handle this migration by either:

• Uploading PST files over your network, or
• Shipping a prepared drive containing PST files directly to Microsoft (after setting everything up according to the service’s guidelines).

To learn more, visit Overview of importing your organization’s PST files.

Migrate Email from Another IMAP-Enabled Email System

If your current email system supports IMAP (e.g., Gmail, Exchange, Outlook.com), you can migrate user mailboxes with that protocol. Keep in mind:

• IMAP migration moves only inbox and mail folder contents (not contacts, calendars, or tasks).
• IMAP migration does not automatically create mailboxes in Microsoft 365 or Office 365; you’ll need to set those up for your users ahead of time.
• An administrator can use IMAP migration to bring over all emails for each mailbox, but after the process finishes, any new emails that land in the original source mailbox won’t be copied.

For detailed instructions, see Migrate your IMAP mailboxes to Microsoft 365 or Office 365.

Have Users Import Their Own Email

Not every migration needs to be managed centrally. Users can import their own email, contacts, and additional mailbox information into Microsoft 365 or Office 365. To learn more, see Migrate email and contacts to Microsoft 365 or Office 365.

If none of the methods above fit your scenario—or you simply prefer expert assistance—consider working with a Medha Cloud to move your email into Microsoft 365 or Office 365. Check out the Office 365 Migration Services page to find a partner who can help.

Users Provisioning for the Different Migration Types

Use this table to figure out which scenario applies to your organization and how the provisioning flows from source to target.

Next Steps & Additional Resources

1. Plan your migration path: Use Microsoft’s advisors to pick the best strategy.
2. Prepare your environment: Make sure you have the right licenses and infrastructure.
3. Perform the migration: Follow the detailed instructions for your chosen approach.
4. Verify and test: Ensure email is flowing correctly and all mailbox data appears as expected.

Migrating email to Microsoft 365 or Office 365 can be smooth and efficient when you know your options and plan carefully. With the above methods at your disposal, you can pick the path that best fits your organization’s size, complexity, and timelines—whether you do it yourself or bring in a partner for extra assistance.

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