title: Download all messages from a Google group
body: <p>I'm in the process of developing a Google apps migration/archive system and at this point in development I'm trying to come up with a way to download all messages in all the groups that my domain users have created. I know that I can set up forwarding filters and have all messages archived to an email, but this doesn't help with older messages.  </p>
  
  <p>Is there a way to download these messages from a Google group and if so, is there away in the admin API to get a list of all groups that users have created?</p>