Microsoft>Customer installations of Exchange 2016 and Exchange 2019 will continue to run after October 14, 2025.
Can you please clarify what this means for installations with a hybrid deployment where Exchange Server 2019 today is a local mail relay to Exchange Online. Will Microsoft take measures that stop Exchange Server 2019 from relaying e-mails to Exchange Online immediately after Oct 14,2025? Or will this fall together with the end of the co-existence with older Exchange Server versions, which is announced for Exchange Server SE CU1?
MicrosoftWill we do it on October 15: no; definitely not.
Does this mean that it will not be done until coexistence is blocked (Exchange SE CU2)? Also no.
Throttling / blocking is not tied to a specific schedule; we do not have a pre-determined plan of when E2016/E2019 fully up to date on October 15, 2025 will start to get throttled/blocked. This is a decision that humans make and it takes into consideration the totality of security payload that was released since (the oldest build that is still allowed and not throttled). We have a pretty generous number of builds right now that are still not throttled / blocked and this would be brought to "present time" only in case of significant security issue.
Throttling / blocking is not a "get up to Exchange SE" mechanism. It is a "do not run significantly out of date servers" mechanism.
Also note that once this does happen (there will come a time when all E2016/E2019 builds are throttled / blocked) - there will still be allowances for getting time for throttling / blocking mitigation as per the feature design. You'll still get the 90 days...
