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

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Important

Effective from December 2022, the classic Exchange Admin Center will be deprecated for worldwide customers. Microsoft recommends using the new Exchange Admin Center (EAC), if not already doing so.

While most of the features have been migrated to the new EAC, some have been migrated to other admin centers and remaining ones will soon be migrated to the new EAC. Find features that're not yet there in new EAC at Other Features or use Global Search that will help you navigate across the new EAC.

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 can also work with a partner to migrate email.

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

For information on choosing the best option for your organization, see Decide on a migration path or Exchange migration advisors.

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 either to upload the PST files through a network, or to mail the PST files in a drive that you prepare.

For more information, 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, only the items in the users' inbox or other mail folders are migrated. Contacts, calendar items, and tasks can't be migrated with IMAP; a user can manually migrate them.

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 emails, 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. For information on how to do it, see Migrate email and contacts to Microsoft 365 or Office 365.

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.

For information on how to find a partner, see the Microsoft solution providers page.

Users provisioning for the different migration types

Exchange Migration Type Source Target Recipient in Target
Hybrid onboarding Exchange > On-premises > Hybrid Org A Exchange > Online > Hybrid Org A Mail User with ExchangeGuid
Hybrid offboarding Exchange > Online > Hybrid Org A Exchange > On-premises > Hybrid Org B Mail User / Remote Mailbox with ExchangeGuid
Cross-tenant Migration Exchange > Online > Tenant A Exchange > Online > Tenant B Mail User with ExchangeGuid + matching attributes
Cutover migration Exchange > On-premises Exchange > Online No recipient (migration service creates the mailbox in EXO)
Gmail migration Google Workspace Exchange > Online Mail User (migration service converts to mailbox in EXO)
IMAP migration IMAP server Exchange > Online Mailbox

Use PowerShell for email migration to Microsoft 365 or Office 365