it doesn't work :( it says apps can only be installed from the web store
Yes it can work download the extension. then get 7-zip: http://www.7-zip.org/Then extract files from it. now go onto chrome and into extensions, and click load unpacked extension and select the extracted folder and there you go! you have the yahoo mail extension!
USELESS, it does NOT work for Mac. The extension is not valid
Now that yahoo is cool again, I want yahoo extension :-) on my new window8 / chrome30 As per Google, after chrome version 18, we need to add"manifest_version": 2,It works ! :-)