[MlMt] Let the Mail-preview show particular header-parts

[Seebs]

On 8 May 2012, at 15:43, Benny Kjær Nielsen wrote:

> By default, it lacks some headers which should be displayed when 
> available, so if you add some of them then you are welcome to send me 
> the result (for example, Resent headers).

Idle question:

Does the format used for this file have expressiveness enough to allow 
things like "please show me the second Received header"?

I ask because I am one fetchmail hop away from my real mail server, and 
displaying exactly one (relevant) received header would be super useful.

-s