2016 and 2019 installations must meet the October 2025 baseline to reach cloud hosted inboxes Microsoft is upping the ante on Exchange Server security, warning that outdated on premises systems will soon be blocked from sending email to Exchange Online. From the second week of September, Exchange Server 2016 and 2019 machines that send email to Exchange Online through an inbound connector of the OnPremises type must be patched to the final public update baseline released in October 2025,...
