On 2020-04-20 Hartmut W Sager wrote:
I tested both 465 SSL and 587 TLS right after encountering the solution, and they both work, though I am under the impression that Gmail favours TLS (whereas I've hitherto always been using SSL). Any thoughts on that?
I've *always* used STARTTLS on 587 in all email setups, and I've never had a problem. It was my understanding that always-immediate-SSL like we use on the http-web was not really the way it evolved on the email side. When it comes to daemons that have to deal with the real world, I prefer to choose most prevalent paradigms, then your problems/bugs will likely have already been solved by others.
YMMV