Governments/ISP/School/Company could ban obvious encrypted SMTP message. Encryption should be done in a obfuscated handshake way. That's what this paper lacks

Governments/ISP/School/Company could ban obvious encrypted SMTP message. Encryption should be done in a obfuscated handshake way. That's what this paper lacks (and this really matters.) Also if you have your own IMAP/SMTP server running, you should really think about some kind of TOR-like relay network to hide your server IP.