title: Sendgrid on Compute Engine not working
body: <p>I setup Postfix with sendgrid just like the guide here: <a href="https://developers.google.com/compute/docs/sending-mail?hl=en#postfixsendgrid" rel="nofollow">https://developers.google.com/compute/docs/sending-mail?hl=en#postfixsendgrid</a></p>
  
  <p>but it's not working. when i run the test command:</p>
  
  <pre><code>printf 'Subject: test\r\n\r\npassed' | /usr/sbin/sendmail myemail@gmail.com
  </code></pre>
  
  <p>I get this error in the log:</p>
  
  <pre><code>Sep  1 11:58:12 instance-1 postfix/qmgr[23412]: 8205A1E38: from=&lt;*******@instance-1.c.mindful-vial-682.internal&gt;, size=301, nrcpt=1 (queue active)
  Sep  1 11:58:12 instance-1 postfix/smtp[23422]: warning: SASL authentication failure: No worthy mechs found
  Sep  1 11:58:12 instance-1 postfix/smtp[23422]: 8205A1E38: SASL authentication failed; cannot authenticate to server smtp.sendgrid.net[208.43.76.147]: no mechanism available
  Sep  1 11:58:13 instance-1 postfix/smtp[23422]: warning: SASL authentication failure: No worthy mechs found
  Sep  1 11:58:13 instance-1 postfix/smtp[23422]: 8205A1E38: to=&lt;myemail@gmail.com&gt;, relay=smtp.sendgrid.net[208.43.76.146]:2525, delay=0.62, delays=0.01/0.02/0.59/0, dsn=4.7.0, status=deferred (SASL
   authentication failed; cannot authenticate to server smtp.sendgrid.net[208.43.76.146]: no mechanism available)
  </code></pre>