Hi,
We currently have an on-prem Ad/Exchange 2013 environment. The local AD users are synced to O365 which we use for various authentication services to custom applications, and we wish to keep it this way (manage O365 users from the On-Prem AD). We would like to now move all exchange mailboxes to exchange online, and then completely decommission the on-prem Exchange servers (manage mailboxes only in the cloud), yet keep DirSync in place, that is, we want users to connect to their exchange online mailbox using their local AD credentials. Im seeing two approaches to this. I would like to get some clarity, confirm im understanding this correctly and get some recommendations.
Hybrid:
Setup a hybrid configuration, move all mailboxes to exchange online, then remove the on-premise server. However, based on
this article, it's easier said than done. "If the last Exchange server is removed, you cannot make changes to the mailbox object in Exchange Online because the source of authority is defined as on-premises". I understand the challenge,
but i don't understand the solution(s). One solution is to keep at least one last exchange on-prem server indefinitely, which isnt ideal for us. I cant find a clear solution for completely removing the last exchange server in a hybrid scenario (if possible).
Im also seeing mentioning the need for extending the scheme, but im not sure what its referring to. Is it referring to running the exchange "Setup.exe /PrepareSchema" after removing the last exchange server so that the AD exchange attributes
are retained?
CutOver:
In this scenario, i would disable DirSync, remove all synced users from Azure AD, perform a simple CutOver migration, and then re-enable DirSync to convert the Azure AD users to an AD Sync user by soft-matching. However, this would still require that i keep
my on-premise exchange server, is this correct? "In either case, if you have DirSync deployed and you are using Exchange Online, you should have an on-premises Exchange server for user management purposes". As such, i dont gain much by taking
this route? Am i correct? Also, to clarify the soft-match process. Say i have an O365 user created with password 123456, and the user was soft-matched with an On-Prem user using DirSync. The On-prem password was ABCDEFG. Does this mean that the users password
is now ABCDEFG?
Pros/Cons:
The advantage of doing the hybrid approach is that i dont need to redo the client outlook profile. Outlook will automatically point to the Exchange online mailbox when migrated. In a Cutover migration, i would need to manually touch each user profile.