title: Sending email to SMTP server from Google Cloud VM, NGinx, Docker Container
body: <p>I have a google cloud compute instance that is hosting docker containers, one of which is nginx with a reverse proxy, connecting to my server.</p>
  <p>My server is trying to send notification emails via an external smtp server. In this case a test gmail account before switching to the company smtp server.</p>
  <p>I have tried the following:</p>
  <ul>
  <li>Opening (Exposing) up port 587 on the different docker containers.</li>
  <li>Adding Postfix with a loopback-only</li>
  </ul>
  <p>From what I have read it seems that google have opened the 587 port for outgoing calls by default.</p>