title: Adding "include:_spf.google.com" to my SPF record - would that authorize all gmail users?
body: <p>I have a domain and I want to use Gmail to send mail from it.
  <a href="https://support.bigcommerce.com/questions/1092/How+do+I+set+up+my+email+using+Gmail%3F#spf" rel="nofollow">The instructions for this</a> are: Add "include:_spf.google.com" to your SPF record.
  My question is: wouldn't that enable every Gmail user in the world to send mail on behalf of my domain and pass the SPF test?
  I must be missing something here.
  <a href="https://support.google.com/a/answer/178723" rel="nofollow">Google also give similar instructions.</a>
  Thank you very much.</p>