[MlMt] Hidden Preference for making new Composer Window have cursor start at the Body or in the Header fields?

[Mike Petonic]

I just spent about 60 minutes looking through the issue reports and 
mailing list archives, and for the life of me, I cannot find what the 
preference is that allows me to specify whether starting a new message 
starts my cursor on the To: line or the Body: section.  I'd changed it, 
but it turns out that I'd rather have it back on the To: line.

Is this documented somewhere?  Since MailMail doc is something that we 
can contribute to, I promise that I'll add it to the doc! :-)

Thanks!
-Mike