Via email: Yahoo! Mail is upgrading: What it means for you.
Dear Mike Cane,
Thank you for being a Yahoo! Mail user for the past 10 year(s). We look forward to bringing you an even faster, safer, easier-to-use Yahoo! Mail very soon.
Then:
You can upgrade now to the newest Yahoo! Mail if your browser is Internet Explorer 7, Firefox 3, Safari 4, or Chrome 5 or newer.
Given posts I have seen in the Opera Support forum, there is some sort on ongoing battle between Yahoo and Opera. Why, I have no effin idea. But people have posted that YMail does not work with Opera after the YMail upgrade.
Hey, Yahoo! This is supposed to be the world wide web. You should work with every browser. Fix it!
Mike Cane’s xBlog 
Simply change your browser identity in opera and it will work with new yahoo mail. I’ve marked my opera to report to yahoo as firefox. You can do that from Settings->Preferences->Content->Manage site preferences->network
Thanks. I’ll probably have to do that when they force all of us to switch to the New YahooMail. Ugh.
Just keep the old classic version of yahoo.It is much better than the new yahoo and old version loads faster than new version.
Using opera 11.50
At some point they intend to force everyone to use new YMail.
When will ymail continue to work with opera mini.
I don’t know. I no longer use Opera on the desktop and am not using Opera Mini on anything. Ask Opera.
i use yahoo’s mobile version – light and easy to use, little or no ads