While reading Yahoo mail blog, I came to know about a nice new addition to the latest release of Mozilla Firefox 3.

If you go to

Tools Menu >>> Options

then go to Applications Tab.

There you shall find a list of different types of contents and next to each content their is a specific action defined. If you select mailto under the column of ‘Content Type‘, next to it from the drop down menu select “Use Yahoo! Mail” as default action. It will make Yahoo mail as default mailto client in Mozilla Firefox 3.