title: getting "530 5.7.0 Must issue a STARTTLS command first." error when sending mail via netcat
body: <p>I'm trying to send an email with netcat, this is what i get:</p>
  
  <pre><code>****-MacBook-Pro:~ ***$ nc smtp.gmail.com 25
  220 mx.google.com ESMTP h8sm66301168eew.16 - gsmtp
  Helo gmail.com
  250 mx.google.com at your service
  MAIL FROM: &lt;******@gmail.com&gt;
  530 5.7.0 Must issue a STARTTLS command first. h8sm66301168eew.16 - gsmtp
  </code></pre>
  
  <p>what is STARTTLS command and what do i need to do with it?</p>