[11.04]-Firefox won't open mailto: using Thunderbird, HELP!!!

[Jesse Palser]

Hi,

Running Ubuntu 11.04 64Bit.
My default email application is Mozilla Thunderbird
and my default Internet browser application is Mozilla Firefox.

When I click on a email link (mailto:) in Firefox nothing happens?
How would I tell Firefox to use Thunderbird for email links?

Thanks...

Jesse