outlook.com MX does not support TLS in 2020.
Scratch that, it may be a more specific issue. I can observe missing STARTTLS capability only from one location.
Okay, I discovered that Outlook.com MXes do not advertise STARTTLS capability to blacklisted IPs.
A general furry public instance. You don't have to be a furry to join. Any and all topics are fair game provided they do not conflict with the Code of Conduct.