Hello everyone,

We're a small shop with 35 users on Exchange 2003 that We want to migrate to Office365 Exchange.

Right now, our existing Exchange 2003 is not a part of our active directory domain. This happened because Exchange 2003 was an ancient system and we only introduced AD later, as we grew.

Ideally, after we finish migration into Office365, we would like to be able to manage users in Office365 via our on-premises Active Directory.

I have a few questions regarding Cutover vs. Staged migrations:

1) Since our existing Exchange 2003 is NOT a part of our our AD, we wouldn't be able to use dir-sync, right? E-mail users + inboxes are simply not a part of AD so nothing would be found on Exchange. I suppose we could try to install dir-sync on Exchange 2003 directly (it has its own domain).


2) If we can't use dir-sync, we can't do a staged migration. Correct?


3) That leaves only the cutover migration as an option. If we go ahead with the cutover migratin, can we still somehow manage users from our on-premise AD? This is the most important question for us.

Much appreciated!

It looks like too complex for 35 users migration. Here is my own vision of your best migration:

1. You perform a cutover migration.

2. Setup Directory synchronization (with password synchronization) against AD domain where accounts are located.

3. Deploy Exchange 2013 Server in account AD domain to perform recipient management.

I think there is no reason to deal with staged, resource and accounts domains, complex deployment for 35 users. Probably you can migrate during weekend.

• Edited by Slava Fedenko 8 hours 33 minutes ago

It looks like too complex for 35 users migration. Here is my own vision of your best migration:

1. You perform a cutover migration.

2. Setup Directory synchronization (with password synchronization) against AD domain where accounts are located.

3. Deploy Exchange 2013 Server in account AD domain to perform recipient management.

I think there is no reason to deal with staged, resource and accounts domains, complex deployment for 35 users. Probably you can migrate during weekend.

• Edited by Slava Fedenko Friday, July 10, 2015 10:54 PM

Exchange 2003 cannot exist without Active Directory, so the Exchange server is either a domain controller with its own domain, or it is part of the domain you use for computers.

I would agree that with such a small number of users keeping it simple is the key to success here.

If your Exchange 2003 server has its own domain:
1. Install Exchange 2013 in your domain and create mailboxes for everyone
2. Install dirsync and set up hybrid environment syncing passwords as well
3. Export mailboxes from Exchange 2003 to PST
4. Import mail to new Exchange 2013 mailboxes
5. Migrate mailboxes to O365 and assign licenses