I just had a though and tried it. In my yahoo mail I clicke the nofollow button in firefox I notive my folders names were do follow so would it be of any value to change them to url to gain links
No, it wouldn't. If you click on a folder name, it won't point to your site but to the folder location. Here is an example: Proper link: <a href="http://yourdomain.com">anchor text</a> what you're trying to do: <a href="http://yahoo.com/webmail/foldername">http://yoursite.com</a>