Office 365 Migration Plan 2

Office 365 Migration – Part 2: Implementation

Chay Douglas Data Migration, Microsoft Exchange, Office 365

Now that you have read Office 365 Migration Plan – Part 1: Preparation,

(What do you mean you haven’t?! Go back and do that now! That’s the most important bit… !)

Office 365 Migration Plan 2

Right as I was saying, NOW you have read Office 365 Migration – Part 1: Preparation, we have a documented plan of action, milestones have been set and all parties involved know what’s coming and what to expect. Finally, we can move onto implementing the migration.

We’ve looked at what needs to be migrated, now we can investigate how to migrate to Office 365. Here we’ll be looking into the techniques involved and configuration options available.

Migration Plan

There are 3 possible Office 365 Migration plans when migrating from an On-premise Exchange environment:

  1. Cutover
  2. Staged
  3. Hybrid



Available to all Exchange environments from 2003+ and generally advised to be utilised when migrating fewer than 2,000 mailboxes, a Cutover migration works in the same way as any other Exchange migration where mailboxes are migrated by moving them directly into Office 365. All handling of the mailbox is completed on Office 365, as are logins and access.

For a more detailed outline, see this article, What you need to know about a cutover email migration to Office 365



Only available to Exchange 2003 or 2007 environments and generally advised to be utilised when migrating in excess of 2,000 mailboxes, a Staged migration has a slightly different approach in the fact that is forced to run an AD synchronisation which replicates the user profiles and copies the on-premise mailboxes to Office 365, as opposed to a move. As soon as the synchronisation is complete and the mailbox is on Office 365, the traffic is sent to/from the newly copied mailbox in Office 365.


During this time, there are two mailboxes for the user. One on-premise and the other in the cloud – which is responsible for all traffic. The user’s Outlook profile, however, is still connected to the on-premise mailbox and therefore cannot see any new emails so would have to log onto the Office 365 mailbox using a browser to have access.


In order to rectify this, the administrator converts the on-premise mailbox to mail-enabled users in Office 365. This then uses the Outlook Autodiscovery service to connect to the Exchange Online mailbox.


Generally, stage migrations are completed in batches so during the migration some users will be on Office 365 and some on-premise. Until all users have been migrated successfully, the entire organisation will not be able to be redirected to Office 365, but this will have to be completed in batches by the previously mentioned conversion of mailboxes to Mail-Enabled using in Exchange Online.


For a more detailed outline, see this article, What you need to know about a staged email migration to Office 365



Only available to Exchange 2010 and 2013 environments, hybrid cloud solutions allows you to combine your on-premises applications or data with cloud-based services to meet your organisation’s needs.


Hybrid would suit is you need to move more than 2,000 mailboxes, don’t intend to move all users, or if you wish to simultaneously run local Exchange servers and Office 365.


A hybrid migration creates user accounts and copies content to Office 365. It also provides a unified shared address book, calendar sharing and the opportunity to move some Office 365 email users back to the local Exchange server again. This is a great place to start when carrying out a migration with Hybrid environment.


At MirrorSphere, we are experts in email migration and we’re happy to talk you through your Office 365 Migration options.


Let MirrorSphere help you migrate to Office 365

Exchange 2007 End of Life
Office 365 Migration Plan: Part 1 - Preparation