If you want a complete configurable Drupal module (administrate->structure->roles-rules), to add/remove this rules and choosing for example the mail domains that you need to check, and specifing all the stuff, my bid is for that. I've got experience in Drupal for many years, and now I'm working on three Drupal projects (two in production, one testing). Although if you prefer a simple module only with this rule I could do one module with a static rule, in two days only for 100$.