We have been working over the last few years to move all of our clients from Microsoft Exchange 2016 and 2019 servers onto more modern and hopefully more secure platforms.
Once Microsoft stops cyber security support for these servers, the threat actors will attack any that are still online.
Microsoft: Exchange 2016 and 2019 reach end of support in October – BleepingComputer
We are ahead of the game are you and your IT support in the same position?
Clive Catton MSc (Cyber Security) – by-line and other articles