Hello,
I have the following environment:
1. Exchange server 2003
2. Windows Server 2003 Domain controller
I have performed the staged migration of all user mailboxes to the Exchange online and set up the Dirsync (AD Connect) with password synchronization, because we plan to manage our users in the on-premises Active Directory.
All users have mailboxes in Exchange Online and now we plan to upgrade the on-premises Active Directory:
1. Convert users that have mailboxes in the EO to mail-enabled users and delete their local mailboxes
2. Uninstall Exchange 2003
3. Introduce Windows Server 2012 R2 domain controllers and decommission the 2003 DC
4. ?
I am not sure on next step though. We want to manage users on-premises. According to information I gathered we need to install on-premises Exchange in hybrid mode and obtain free Hybrid license (http://blogs.msdn.com/b/vilath/archive/2015/05/26/office-365-and-dirsync-why-should-you-have-at-least-one-exchange-server-on-premises.aspx)
There will be no more on-premises mailboxes, but users will be managed on-premises.
The question(s) are:
Can I simply install Exchange 2013 Server and configure hybrid mode after uninstalling Exchange 2003 from the domain?
Is there anything I need to configure additionally or change on existing mail enabled users in the AD to make this scenario work?
Thank you for any hint