Just an idea: it might save you time reading and others' time writing lots of posts if there were a sticky thread at the top of this section (like "Supported Systems & Browsers") that would explain the email situation (like "Having Connection Problems? Look Here"). For the sake of anyone still having problems, here's what worked for me: if you're willing to have a new username, I went to dominion.games and signed up with a new username and password. Unfortunately, that takes you to a screen that says "Signing you up!" which I assumed would go away once the process was complete and let you into the game so I left it there for a long time. Eventually I closed the window then went right back to dominion.games and it let me in. However, I couldn't host a game because I'd get a window saying you can't host until your email is confirmed. To solve this, go to the Account button, retype in your email address, hit the Confirm button, and you should get a window saying an email has been sent to confirm your email address. Check your email and you should soon be good to go.
If you're married to your old username, my group is 2 for 4 at getting the welcome email finally about 3 hours ago so the wait may soon be over.