Set Firefox mailto links to GMail/Googlemail
Nice easy tip this one.
Open Firefox, and open up GMail/Googlemail.
Paste this command into the address bar with the GMail/Googlemail page on view
javascript:window.navigator.registerProtocolHandler(”mailto”,”https://mail.google.com/mail/?extsrc=mailto&url=%s“,”GMail”) << all one line
and click on green arrow
Firefox will ask if you want to add the application, to which you say yes.
Now click on a mailto link, and Firefox will ask you which email client you wish to use. Select Googlemail and also tick the box to allow this to persist.
Job done 