title: What does ESOCKET error mean when I'm trying to send an email?
body: <p>I'm trying to send an email using nodemailer.</p>
  
  <p>In my LAN there is a SMTP server listening on port 25. If I use telnet, it works fine.</p>
  
  <p>My js script is:</p>
  
  <pre><code>this.transporter.sendMail(mailOptions, function (error, info) {
          if (error) {
              console.log(JSON.stringify(error));
              return callback(error, null);
          }
  
          console.log(JSON.stringify(info));
  
          return callback(null, true);
  });
  </code></pre>
  
  <p>It only prints: {"code":"ESOCKET","command":"CONN"}. What does it mean?</p>
  
  <p>Thanks in advance</p>