Fixed issue: wrong port and TLS description in bounce email/smtp settings (#1639)

• Fixed issue: wrong port and TLS description in bounce email/smtp settings

Dev: As per imap_open() manual {hostname/ssl} could be actually both SSL or implicit TLS connection depending on PHP configuration/version, which almost always uses standard IMAPS/POP3S ports. And {hostname/tls} means that a client requires a server to allow STARTTLS which usually runs on the same port as plain text IMAP/POP3. Make sure we won't set wrong port here if an administrator didn't specify one.

Dev: The same goes for SMTP connection and PHPMailer library. If "tls" is specified the SMTPSecure option in the library initiates STARTTLS support not the implicit TLS connection, see https://github.com/PHPMailer/PHPMailer/blob/master/src/PHPMailer.php#L2024

Dev: While at it, inform administrators that not using SSL/TLS or StartTLS makes a connection very insecure.

Dev: Also, make values lowercase as most of their default options in the code are lowercase.

• Fixed issue: wrong port and TLS description in bounce email/smtp settings

Dev: fix setting description in the comments too

• Fixed issue: wrong port and TLS description in bounce email/smtp settings

Dev: Convert the values already set in the database to lowercase too.

• Fixed issue: wrong port and TLS description in bounce email/smtp settings

Dev: one more place to convert the value already set in the database to lowercase