My handle is: @email@example.com
Quick tip for those joining: I was stuck on the choosing-a-server step for a very long time, until I realized account creation is a bit like creating an email account. You don’t really care whether someone has an email at Gmail, Yahoo, or their own self-hosted server. So just pick a server that has a content moderation policy and ideology you most agree/identify with and sign up there! And thanks to federation, you can always contact users on other servers, so don’t worry if you can’t sign up on a particular server.