Upon dozens of failed attempts, the mail seems to finally work now, or at least for GMail.
We apologize to everyone that couldn't create their forum past week and this week.
In case you have registered a forum and didn't receive the mail and want to re-create it, please reply to this thread or mail us at info@freeflarum.com. I will remove the "broken" forum, so you can re-create it and receive the password.