Having issues with setting up mail to smtp.office365.com

We’re trying to get our email settings updated to hit 365 and we’re having all kinds of issues. Per the article, https://launchpad.support.sap.com/#/notes/2684855, we’re entering everything correctly. However, my publications fail with a generic reason. If I change it back to our old hybrid mail server, it works. I keep seeing something about a certificate, but our System Admin says we do not have cert authentication.

Anyone had any issues with getting the mail to connect to o365?

I cannot refer to o365.
I would try from bo server(s) try to check if a firewall is opened and if o365 allows to use plain / unsecured communication (without any extra settings) - sounds weirdly - these days…
T.