About a year ago, we announced Exchange Server Security Changes for Hybrid Deployments. This change impacted Exchange hybrid customers who host some of their mailboxes on-premises and their on-premis...
Updated Aug 31, 2026
Version 6.0
Blog Post
Nino_Bilic
Microsoft
MicrosoftWith no mailboxes on premises, you can do it whenever you want. There is no "rich coexistence" between on-prem and online users because there are no on-prem users.
We have user mailboxes hosted in a different site and servers. Only one site has legacy 2016 servers where we don't have any mailboxes. Are we still good to go and update our hybrid config to use Graph API or we wait until we decommission legacy servers?
- Nino_Bilic
If there are no mailboxes hosted on legacy servers then you are good to go. Again, this whole thing is about on-prem hosted mailboxes trying to look up F/B etc. for online mailboxes. But you do not have mailboxes hosted on servers that cannot use Graph so... change away.