title: How can I use Devise Authentication to validate that a sign up email address is from certain domain?
body: <p>I would like to make sure the only people with email address of a certain domain can signup for a site that is using Devise.</p>
  
  <p>For instance if people sign-up with the email joe@mysite.com, they should get a confirmation email but if the sign up with joe@yoursite.com, they should get a error message.</p>