…if you run your own onsite Exchange server.
Keeping onsite Exchange servers up to date and patched was a labour intensive task, when our support team used to do it – now we no longer support any on premise Exchange servers it is a relief for the team. But for IT support teams that are not so vigorous in their patching or worst still, you work in the accounts department and part of your job is the company IT, when those onsite Exchange servers fall behind in security patches, Exchange Online servers will throttle and eventually block email from them, as it poses a security risk.
Exchange Online to block emails from vulnerable on-prem servers (bleepingcomputer.com)
This will also apply to Exchange servers that have exceeded or are near to their EOL, so that is everything except Exchange 2016 and 2019.
My advice: Either you or your IT support need to check whether these issues impact your systems. You need to have a master document that details your systems, hardware, software, online, networks, back-ups, suppliers etc – so when cyber security (or operational) issues arise you and your support teams can quickly check if you are affected. From there you can take fast, effective action.
