Allow unsecure SMTP mails
As of PHP 5.6; a valid certificate is required to send mail with SMTP and on recent PHPMailer, TLS encryption is automatically set on if server has capabaility.
Allow unsecure SMTP connection on some cases
Allow "unsecure" SMTP connections if user has asked fot it or
if user did not request TLS explicitely.
Tha "ask for it" UI part is not done yet.