$ telnet smtp.gmail.com 587
Trying 173.194.67.108...
Connected to gmail-smtp-msa.l.google.com.
Escape character is '^]'.
220 mx.google.com ESMTP ea6sm27303065wib.5
HELO zwp
250 mx.google.com at your service
AUTH PLAIN [elided]
530 5.7.0 Must issue a STARTTLS command first. ea6sm27303065wib.5
$ telnet smtp.gmail.com 587
Trying 173.194.67.109...
Connected to gmail-smtp-msa.l.google.com.
Escape character is '^]'.
220 mx.google.com ESMTP ff2sm43397967wib.9
HELO zwp
250 mx.google.com at your service
MAIL FROM:<test@example.com>
530 5.7.0 Must issue a STARTTLS command first. ff2sm43397967wib.9
Please try your test again on port 25, which is the port that server-to-server e-mail would use, as the post above yours said that it is possible to send e-mail to @gmail.com without using STARTTLS. This is, in fact, not only possible but required. Otherwise, @gmail.com would be inaccessible to any e-mail address using an MTA that does not support or is not configured for TLS.
