I have never recieved an activation email for the beta. I paid via paypal and it went through fine. I also tried changing my password, but I still did not get an email in either my spam or inbox.
My email is firstname.lastname@example.org
It seems others have issues as well, if it works better you can try email@example.com if you are able to change it, does not matter to me.
I can forward the receipt if needed.
I also did not pay long ago, so maybe the mail takes some time and i am just a little excited to try the beta out too