Don't worry, it's like many "cute" restrictions -- they didn't do a good job. Just capitalize your email and it'll sail right through. It's also only checked on registration, so you can continue to use the lowercased version to login.

It's without the tiniest sense of irony one will observe the "Signin with Google" button on the login form, too :-/

ed: although I may have ruined it for everyone, since my "team name" is now "GMAIL.COM" :-P

      "team": {
        "id": 29,
        "name": "GMAIL.COM",
        "tier": "Free"
      }

Sorry about that! But its actually the registration for signup and not for updates. Thats why we had to block personal emails.