The Simplest one is mentioned here but Please read the comments below the post- lot of ways have been mentioned to switch back to Yahoo Mail Classic !
1) Disable Java Script in your Browser !
3) GO Ahead and do that !
4) (optional) Enable Java Script !
Enjoy the Yahoo Mail Classic ! :)
PS : After enabling Java Script, if at a later stage, if the New Yahoo Mail shows up, don’ worry Just repeat the above process ! I personally had to do it 10 – 15 times and after which the New Yahoo Mail never showed up !
This technique mentioned below does not work anymore !
Yahoo has now introduced yet another Mail beta which is largely better that the previous. But, in case you want to switch back Mail Classic – the procedure is a little different now. Earlier, there was an option below the Yahoo Mail Beta Icon, “Switch to Mail Classic“. But now this has moved to Help Menu at the top left. Click on the drop down to find an option called “Return to Original Mail“. The snapshot below will help you understand things better.