Ways to migrate multiple email accounts to Microsoft 365 or Office 365

Your organization can migrate email to Microsoft 365 or Office 365 from other systems. Your administrators can Migrate mailboxes from Exchange Server or Migrate email from another IMAP-enabled email system. And your users can import their own email, contacts, and other mailbox information to a Microsoft 365 or Office 365 mailbox created for them. Your organization also can work with a partner to migrate email.

Before you start an email migration, review limits and best practices for Exchange Online to make sure you get the performance and behavior you expect after migration.

See Decide on a migration path or Exchange migration advisors for help with choosing the best option for your organization.

Tip

Another option available to assist you with your email migration is FastTrack Center Benefit Overview. FastTrack specialists can help you plan and perform your migration. For more information, see Data Migration.

You can also view an overview video:

Migrate mailboxes from Exchange Server

For migrations from an existing on-premises Exchange Server environment, an administrator can migrate all email, calendar, and contacts from user mailboxes to Microsoft 365 or Office 365.

An administrator performs a staged or cutover migration to Microsoft 365 or Office 365. All email, contacts, and calendar information can be migrated for each mailbox.

There are three types of email migrations that can be made from an Exchange Server:

Use the Import Service to migrate PST files

If your organization has many large PST files, you can use the Import Service to migrate email data to Microsoft 365 or Office 365.

An administrator migrates PST files to Microsoft 365 or Office 365.

You can use the Import Service to either upload the PST files through a network, or to mail the PST files in a drive that you prepare.

For instructions, see Overview of importing your organization's PST files.

Migrate email from another IMAP-enabled email system

You can use the Internet Message Access Protocol (IMAP) to migrate user email from Gmail, Exchange, Outlook.com, and other email systems that support IMAP migration. When you migrate the user's email by using IMAP migration, only the items in the users' inbox or other mail folders are migrated. Contacts, calendar items, and tasks can't be migrated with IMAP, but they can be by a user.

IMAP migration also doesn't create mailboxes in Microsoft 365 or Office 365. You'll have to create a mailbox for each user before you migrate their email.

An administrator performs an IMAP migration to Microsoft 365 or Office 365. All email, but not contacts or calendar information, can be migrated for each mailbox.

To migrate email from another mail system, see Migrate your IMAP mailboxes to Microsoft 365 or Office 365. After the email migration is done, any new mail sent to the source email isn't migrated.

Have users import their own email

Users can import their own email, contacts, and other mailbox information to Microsoft 365 or Office 365. See Migrate email and contacts to Microsoft 365 or Office 365 to learn how.

A user can import email, contacts, and calendar information to Microsoft 365 or Office 365.

Work with a partner to migrate email

If none of the types of migrations described will work for your organization, consider working with a partner to migrate email to Microsoft 365 or Office 365.

To find a partner, use the Microsoft solution providers page.

Use PowerShell for email migration to Microsoft 365 or Office 365