To get Yahoo Mail Beta, just switch your content preference to Germany, Frence or UK. Then you will be asked if you want to join the beta when you log into your Yahoo Mail. Say yes, and join the beta. Then from the options menu, change your content preference what it was before. Then go to Yahoo Mail again. You should still see Yahoo Beta. If you don’t see it, go to options and click “Try Beta� button. That’s all.