migrating exchange 2003 to Office365

First of all, I'm not familiar with Azure Office 365 and see if I can just for one step migration without downtime.

We have AD with forest and domain functional level 2003 and Exchange server 2003.
There are not many users for this small business, about 70 user mailboxes.
I have to suggest my boss which way is better to go either on-premise or Azure office 365.
For on-premise, as I researched, I have to go through two step upgrades for AD and exchange server, 2008 -> 2016.
Instead, is it possible just go directly from on-premise exchange 2003 to Office 365? If then, how does it work with our current AD? Do I still raise forest/domain functional level to 2012? I am trying to figure what is the damage during the upgrade because this business is 24 hour operation, have to minimize the downtime.
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Todd NelsonConnect With a Mentor Systems EngineerCommented:
If you use a 3rd party tool like MigrationWiz you should be able to migrate from Exchange 2003 to Exchange Online without installing any new Exchange servers.


  1. Create your O365 tenant;
  2. Your Exchange 2003 environment has to be accessible from the outside via OWA;
  3. Then configure your databases with the correct permissions;
  4. Log in to the MigWiz console to create a project;
  5. Copy mailbox data from Exchange to Exchange Online with MigWiz project;
  6. Perform a DNS cutover from on premises to O365;
  7. Perform a final migration;
  8. Use DeploymentPro to reconfigure Outlook clients (optional).

This process requires relatively no to very little downtime.


Also take a look at CodeTwo, BinaryTree or others to perform something similar to migrate to Exchange Online.

☁ François Peroux ☁Connect With a Mentor Infrastructure ConsultantCommented:

If you want to keep Exchange 2003 and move to Office365, you don't have the choice to do a cutover migration. It's something you have to plan since you'll have downtime.

Or you can update the Exchange Server to 2016 and you'll have more option (remote move migration for example) and it'll be more transparent for users and avoid a painful downtime.

You have all the details on this article :

Scott CSenior Systems EnginerCommented:
@Francois...you cannot update Exchange 2003 or 2007 for that matter directly to Exchange 2016.  What would have to be done would be to do a migration to Exchange 2010, remove Exchange 2003 THEN migrate to Exchange 2016.
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☁ François Peroux ☁Infrastructure ConsultantCommented:
@Scott, thanks for the details. I didn't detailed the process of Exchange update but it was the idea.
☁ François Peroux ☁Infrastructure ConsultantCommented:
MigrationWiz is also a really good third party tool we used often. You just have to know that this solution is not free, you'll have to pay per user you migrate.
I second what Todd says....I have done a few migrations using MigrationWiz for Exchange 2003 and it makes it easier than doing a double hop migration. You do have to pay per mailbox for MigrationWiz
Tej Pratap Shukla ~DexterServer AdministratorCommented:
Hi crcsupport,
I understand that manual approach to migrate Live Exchange Server mailboxes to Office 365 is a lengthy and tiresome procedure. So, I would suggest you to use an automated solution that would efficiently perform Exchange to Office 365 Migration.

I hope this solution works well for you.
Do let me know about the results.
Ajit SinghCommented:
Exchange 2003 Cutover Migration to the NEW Office 365: http://office365support.ca/exchange-2003-cutover-migration-to-the-new-office-365/

In addition to above few more third party migration solutions out there like, Metalogix or LepideMigrator for Exchange to accomplish this migration task easily and efficiently.

Hope this helps!
Todd NelsonSystems EngineerCommented:
You should have enough information to complete your request.
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