hello Exchange Team Blog
I see your article states:
2/20/2025: Please note that thottling/blocking has now been enabled for all versions of Exchange Server, including Exchange Server 2019, if significantly out of date.
and
We will also send targeted Message Center posts to customers 30 days before their version of Exchange Server is included in the enforcement system.
However I have double checked our Message Center for the words 'blocked', throttled', 'throttling' and can find no such posts?
I have also checked through my archive of old 'Major update from Message center' and 'Weekly digest: Microsoft service updates' emails from the past few years and again cannot find any mention of this?
The first I am hearing about this is right now, when finding the error:
Connecting Exchange server version is out-of-date; connection to Exchange Online throttled
while troubleshooting delays passing through our (admittedly slightly behind) on-prem infrastructure.
I know the aim is to get people fully updated, but discovering emails are going to start being blocked in only 2 weeks time is not a great way to find about this...