[redirect] How to redirect to a different domain using NGINX?

server_name supports suffix matches using .mydomain.com syntax:

server {
  server_name .mydomain.com;
  rewrite ^ http://www.adifferentdomain.com$request_uri? permanent;
}

or on any version 0.9.1 or higher:

server {
  server_name .mydomain.com;
  return 301 http://www.adifferentdomain.com$request_uri;
}