I have a domain with a - in it. It seems that the email domain will accept but it will not allow you to create any users under that domain. To test I used the domain test.com it works I was able to create a user firstname.lastname@example.org Then I created a domain test-test.com I was not able to create any users. It says that user already exists to any name. a fix would be appreciated. Since I now can't use it as my email server.