Microsoft Exchange 2003 to Office 365 Migration
System Notes: Microsoft Exchange Server 2003 Enterprise, Microsoft Office 365 E1
I have just recently completed a migration from a legacy on-premises Exchange 2003 e-mail server (running Exchange 2003 Enterprise; only one server/one mail database; 85 user mailboxes) to Microsoft Office 365 (cloud-based e-mail solution; using plan E1). Here are some of my personal observations and recommendations for this process:
- I consulted with 3 different “migration” companies, but ultimately ended up doing this process myself with no outside help. The cheapest of the 3 companies was over $4K for assistance with the 85 mailboxes we had to migrate. The worst part of the migration process was converting each of the on-site Outlook 2010 clients to connect to Office 365, as it ended up taking the most time and being the most disruptive to the users. None of the companies offered to have someone on-site to help with this process, or wanted even more money specifically for that. Save yourself some grief and hire a temporary contractor for this portion of the project, as the rest of the actual migration is not hard at all, assuming you have a good plan in place.
- We used the Exchange RPC interface to do a “cutover” migration from the Exchange 2003 server. Two notes on this process:
1. I was able to stop, restart, delete, and recreate the batch migration I set up as needed, with no duplication of users or any data in the user mailboxes. I was very worried about this initially, and could find no hard data on it online, so I decided I would just delete the mailboxes and re-migrate if duplication became a problem (which it did not).
2. Existing mailboxes that had the same username as those that were being migrated were blocked from migration and had to be completely deleted before they could be imported successfully. We have multiple domains set up on Office 365, and I had 5 test accounts set up with a domain that was different from the one I was migrating from Exchange 2003. However, the usernames were the same, and this is where I discovered the issue.
- Do not just shut down your Exchange server once the migration is complete and you are running fully on Office 365. Even the older Exchange 2003 integrates extensively with Active Directory, and it must be uninstalled correctly or you are bound to have problems with Active Directory in the future. This is what I did:
1. Removed all mailboxes from the Exchange 2003 server.
2. Added a correct primary e-mail address that corresponded with the Office 365 e-mail address under the primary SMTP address field in Active Directory for each user. This is necessary for several Active Directory to Office 365 automation routines that we use, and may be required as well if you are using any of the directory synchronization routines that Microsoft provides.
3. Before uninstalling Exchange itself, I removed all supporting programs, including our Backup Exec Exchange agent, the Exchange User Monitor, and the Exchange Auto-Accept Agent.
4. If you get an error message when trying to uninstall Exchange 2003 from Add/Remove Programs, check out this link for a possible solution. We had one user account that the mailbox had been successfully removed from, but that still had the Exchange attributes attached in Active Directory. I was able to remove these via the Exchange user wizard. I did not have to remove the SystemMailbox from our Exchange environment, but I have seen others indicate they had to do this in their environments.