title: how to change default email address for postfix?
body: <p>I have a server running python, php, perl, ruby, and I have couple applications which also send mail. I was wondering in case if one of the applications don't specify a from email address, the sender email address is set to <code>http@example.com</code> and the sender name was "http". </p>
  
  <p>I was able change the sender name by going into <code>/etc/passwd</code> and changing the name to what I wanted, but how do I change <code>http@example.com</code> to <code>admin@example.com</code>?</p>