Set Gmail as your default email client in Firefox
1) Go to Gmail and sign in.
2) While in Gmail, copy and paste the following into your browser’s address bar and hit enter.
javascript:window.navigator.registerProtocolHandler(“mailto”,”https://
mail.google.com/mail/?extsrc=mailto&url=%s”,”Gmail”)
from: Official Gmail Blog: Tip: Set Gmail as your default email client in Firefox 3
3 years ago