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.
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.
There are three types of email migrations that can be made from an Exchange Server:
Migrate all mailboxes at once (cutover migration) or Express migration
With cutover migration, you can move up to 2000 mailboxes, but due to length of time it takes to create and migrate 2000 users, it's more reasonable to migrate 150 users or less.
Migrate using an integrated Exchange Server and Microsoft 365 or Office 365 environment (hybrid)
Use this type of migration to maintain both on-premises and online mailboxes for your organization and to gradually migrate users and email to Microsoft 365 or Office 365. Use this type of migration if:
You have Exchange 2010 and more than 150-2,000 mailboxes.
You have Exchange 2010 and want to migrate mailboxes in small batches over time.
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.
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.
Are you looking to move to the cloud and easily migrate to Business Central online? This module covers how you can use the built-in migration tools to migrate data to Business Central online from specific product versions.
If you’re an administrator who deploys and manages Microsoft 365 and performs Microsoft 365 tenant-level implementation and administration of cloud and hybrid environments, this certification is designed for you.
There are many paths to migrate data from an on-premises email organization to Microsoft 365 or Office 365. When planning a migration to Microsoft 365 or Office 365, a common question is about how to improve the performance of data migration and optimize migration velocity.
You can migrate the contents of user mailboxes from your source email system to Microsoft 365 or Office 365 using the Internet Message Access Protocol (IMAP).
As part of a Microsoft 365 or Office 365 deployment, you can migrate the contents of user mailboxes from a source email system to Microsoft 365 or Office 365. When you do this over time, it's called a staged migration. A staged migration is recommended when:
Deciding on the best migration path of your users' email to Microsoft 365 or Office 365 can be difficult. This article gives guidance based on your current email system and other factors, such as how quickly you want to migrate to Microsoft 365 or Office 365. Your migration performance varies based on your network, mailbox size, migration speed, and so on.
