Why does Gmail hate my domain?
If the domain is bitbin.de and the mail server is hosted on the same server, it's probably Hetzner being scorched-earth for deliverability, just like any other major hosting provider will be. Email from AWS, Rackspace, Heroku etc. get a drastically higher starting spam score because people fire up servers there to spam.<p>Running the email through something like Amazon SES or Mandrill would probably be helpful. Both have generous free tiers.