There is actually a hack to get around this - I don't know if its still there but I did it a couple of hours ago and it worked: 1) Copy the link from the email

There is actually a hack to get around this - I don't know if its still there but I did it a couple of hours ago and it worked: 1) Copy the link from the email (right click on the red button in the email and save link location) 2) Open another browser or incognito tab that you're not logged into. 3) Create an @gmail.com account or use an existing one if you have it and paste the link in the address bar once you're logged in. It seems like the invite is just the token in the link, it's not specifically linked to a given email.