Forum Discussion
Questions for Exchange 2016 to EXO
Hi,
I have a few questions regarding a migration/transition to Exchange Online.
I'm new to this environment but we are currently running Exchange 2016 and will deploy Exchange 2019 during the summer and then upgrade to Exchange SE during the fall. I know 2016/2019 will be unsupported in Oct.
We recently got the thumbs up for moving to Exchange Online for the majority of mailboxes but we will keep a few on-premises servers to host some mailboxes as well as acting as a mail-relay for a few servers/systems.
Im throwing a few questions I have here while I'm trying to search and read the articles online:
Questions/comments:
- We have the sync to Entra ID up and running so that part seems OK
- We will run the HCW and establish a hybrid between the current Exchange 2016 environment and Exchange Online. MX shall still be pointing towards on-prem. When Exchange 2019/SE is deployed we will run the HCW again to link the new servers.
- Do I need to run the HCW while on Exchange 2019 and then again after the servers are upgraded to Exchange SE? Or are they concidered the same servers and this is like a CU?
- In terms of mailboxmigrations and DNS entries like mail.company.com and autodiscover.company.com. How can we plan and manage so its seamless for the users?
- Shall we keep mail and autodiscover for internal lookups pointed to the current on-premises environment (via hardware load balancer) and add the external ones pointing towards EXO?
- If internal clients still on Exchange 2016 starts Outlook they will still use internal DNS and connect to the Exchange 2016 environment?
- If external clients starts Outlook they will connect to Exchange Online and proxied back to its mailbox on-prem? (if they are not yet migrated)
- If a mailbox is moved, internal outlook clients will be proxied to Exchange Online?
- If a mailbox is moved, external outlook clients will stop the proxy and connect directly to the mailbox in Exchange Online?
- After a mailbox migration, will the enduser see the "Please restart Outlook notification?"
- Are mailboxes still on-prem able to connect to a shared mailbox hosted online?
- Are mailboxes online able to connect to shared mailboxes hosted on-prem?
- Shall we keep mail and autodiscover for internal lookups pointed to the current on-premises environment (via hardware load balancer) and add the external ones pointing towards EXO?
Thanks for your help and hope the answers bring some clarity so we can start planning for the migration strategy.
1 Reply
the Exchange Deployment Assistant is your friend here. A couple of points:
- autodiscover needs to point to on-prem Exchange if you have Outlook clients outside your corporate network connecting to on-prem mailboxes. If you don't have this scenario, then you can point autodiscover to EXO. So generally you wouldn't make this change until all mailboxes are migrated (EXO won't redirect Outlook clients back to on-prem Exchange, but Exchange on-prem will redirect to EXO)
- Once a mailbox is migrated, the Outlook client will generally be reconfigured to point to EXO (that's what autodiscover does), so there won't be any proxying for either internal or external
- To reduce any impacts, always migrate shared mailboxes (including calendar delegation) at the same time as users who have the delegate permissions. In theory an EXO mailbox can access an on-prem mailbox, depending on the permissions (and vice-versa), but we've always seen issues, so migrate them both so you can guarantee no issues (especially the critical ones)
