I don’t know if it is a implementation problem, a bug or a configuration problem bur here we go.
Can not send email through a smarthost, port 465 (SSL)
Error in /var/log/maillog
Jul 23 22:47:44 gemini default/smtp: CLIENT wrappermode (port smtps/465) is unimplemented
Jul 23 22:47:44 gemini default/smtp: instead, send to (port submission/587) with STARTTLS
Port 25 (unencrypted) works well
Can not test port 587 (STARTTLS) because is not suported by the ISP