title: Change smtp outgoing port on PostFix
body: <p>I have PostFix set up and everything is working, except I can't send emails. Now I know most ISPs ports block port 25, as can be seen in this error log entry:</p>
  
  <pre><code>Jan  2 04:29:08 mail postfix/smtp[5835]: connect to gmail-smtp-in.l.google.com[74.125.134.27]:25: Connection timed out
  </code></pre>
  
  <p>but I know there are alternate ports, like 587. How do I change PostFix so that it tries to connect to <code>gmail-smtp-in.l.google.com</code> on port 587 instead of 25?</p>