Just used /discourse-doctor and got the following error on mail test:
Not able to send email Net::ReadTimeout
Then I set DISCOURSE_SMTP_FORCE_TLS: true as recommended here: Cannot send email - problem with port 465 - #10 by schungx
But this time I got the following error:
TLS and STARTTLS are mutually exclusive
So, then I tried to test the TLS connection setup with openssl
openssl s_client -connect 127.0.0.1:465 -debug -msg
So that command failed as well. The connection was established but no negotiation at all.
CONNECTED(00000003)