Muttator is a free browser add-on for Thunderbird, which makes it look and behave like the Vim text editor. It has similar key bindings, and you could call it a modal mail client, as key bindings differ according to which mode you are in.
|File Size||358.64 kB|
|Operating System||Windows 7 Windows XP Windows Vista Windows|
|System Requirements||Mozilla Thunderbird 3.3a1|