A lot of friends had been asking me as to how my Yahoo Mail Beta would work on Ubuntu Linux or for that matter any place else, so I am writing about it here.We start from the basics of the problem to solve it (college taught me something didn’t it ;) ) How does Yahoo know i am not using Windows XP ? Answer is your user agent , the browser communicates your user agent to any site you access. Any workaround?In Opera : No easy way, but in Firefox one can edit the useragent easily and that’s what’s going to help us.

Step 1 : Backup Everything , Although the step doesn’t involve anything risky AFAIK, I still tell you to backup and release myself from liability. In this case just remember the key value that you are going to edit or even better make it blank!

Step 2 : Type about:config in your address bar

Step 3 : Right Click on any entry, Select new string and enter string name as ‘general.useragent.override’.

Step 4 : Take Your Pick Mozilla Firefox versions from http://en.wikipedia.org/wiki/User_agent#Browsers

You might want to replace the version at the end to suit your version of Firefox.

Click on the image below to see the error Yahoo Mail Beta gives, i uninstalled Ubuntu so i cant confirm whether its started to work there, but people say it works in Dapper, See comments also. I can confirm though it doesnt work in Windows Me.
Yahoo Mail Beta Error