An update was automatically installed this morning and immediately stopped my send & receive function. When I uninstalled it, my emails started flowing again.
Does Microsoft know about it?
Most likely, the update that was installed has noting to do with Send/Receive functionality so it is unlikely that the update is the actual cause of your issue.
However, in general, an update does update the built number of Outlook and the outlook.exe file.
When you have a 3rd party firewall tool which checks built-numbers or whether the outlook.exe file is still the same outlook.exe file that you allowed, than you must reconfigure your firewall to allow Outlook access to the Internet again.