Email is a critical component of any IT environment and Office 365 Exchange Online is king when it comes to email in the cloud. Email, contacts, and calendars are often the first IT components to be migrated to the cloud and as a result, there is a great ecosystem of migration tools for Exchange Online.
As with all migrations, we begin by understanding the source and destination of the data. If the source is an existing Exchange server, then there are many tools available, including MigrationWiz from BitTitan, SkyKick, and native Exchange migration tools in Office 365. These tools can also easily migrate mail from other sources such as IMAP, POP, and Amazon Workmail.
The typical migration process includes a “pre-stage” pass through the mail to transfer the bulk of the email, followed by incremental delta passes to keep the source and destination mailbox synchronized. At cutover time, the MX records are changed from pointing at the source system and Office 365 Exchange Online, while user devices are configured to point at Office 365 Exchange Online.
Email migration tools simplify the entire process and create a step-by-step plan to migrate mail non-disruptively. If a third-party spam filtering tool like Mimecast or Proofpoint is in use, the process is further simplified by changing the mail destination inside of the spam filter without the need to change MX DNS records and waiting for them to propagate.
On the destination side of the equation, Exchange Online comes in two popular plans: Exchange Online Plan 1 (EOP1) and Exchange Online Plan 2 (EOP2). These can be purchased as a standalone license for $4 and $8 respectively, or as part of a larger Office 365 or Microsoft 365 suite. For example, EOP1 is included with Office 365 Business Premium, while EOP2 is included with Office 365 E3. The major differences between EOP1 and EOP2 center around enterprise functionality like legal hold archiving, data loss prevention, and encryption. Also, EOP2 offers a 100GB mailbox while EOP1 is limited to 50GB. In either case, the mailbox limit is very high - remember the days of setting 100MB quotas on user mailboxes? - and there is an unlimited personal archive available with both plans, making .PST files a thing of the past.
Email Migration Process
Before starting an email migration, you need to carefully consider what the cloud Directory will look like when everything is done. Will your customer be in a pure cloud Azure AD scenario, or will they need to maintain their existing Active Directory for legacy applications or virtual desktops workloads in Azure?
If Azure AD is the way to go, then you can allow the email migration tool to create the user objects, assign mailboxes, and migrate the data. However, if you need to retain Active Directory on-premises or in Azure, you will need to use the Azure AD Connect synchronization tool to populate the Azure AD with the existing Active Directory user objects. You can then assign mailboxes and use a migration tool to migrate the data into these new mailboxes.
Remember that in Office 365, which sits on top of Azure AD, user objects are not the same as Exchange Online mailboxes. Users in Azure AD are identity objects, which may or may not have Office 365 licenses assigned to them. Assigning an Office 365 Exchange Online license will create a new mailbox. This mailbox can exist independently of the user object. For example, a user’s mailbox can be converted to a “shared mailbox” without an associated user account.
Refer to the Directory section of this post to understand the various options available for migrating users to the cloud.
Strategies for virtual desktops, other applications, printing, and scanning are available on the next page to help you wrap up a successful migration to Azure.