title: Mailgun production and development settings
body: <p>I'm currently integrating a Rails app with Mailgun and I want to make sure I understand how production and development settings should be setup.</p>
  
  <p>If I have different api-keys, is it true that the mailing lists that I create will not be visible when I use a different api key?</p>
  
  <p>I want to make sure I can test things in development and isolate them from my production settings.</p>
  
  <p>I had a sandbox domain setup but it wasn't even sending emails out so I am a bit confused.  Do I need to create a test subdomain?</p>