I tried inviting myself, using one of my other e-mail addresses that is not registered, just to see how the invite system works…
I received the e-mail, but when clicking on the link, I see:
Sorry! This invitation is intended for new users, who do not already have an existing account.
I searched my users to make sure that I hadn’t used that e-mail address, and it doesn’t show up anything. Do I have a setting incorrectly set?