[MlMt] Monospaced font when reading messages?

[Muster Hans]

Hi,

Mail programs I have used previously have had an easy way to display the 
current message in a non-proportional font, which makes it easy to read 
the output of text based reports such as those output by Terminal 
commands:

For example, here's the first few lines of the 'top' command in 
Terminal:

PID   COMMAND      %CPU TIME     #TH  #WQ  #POR #MRE RPRVT  RSHRD  RSIZE 
  VPRVT  VSIZE  PGRP PPID
6383  launchproxy  0.0  00:00.00 1    0    19   26   136K   216K   500K  
  27M    2386M  6383 1
6382  top          3.8  00:00.81 1/1  0    26   30   868K   216K   1616K 
  17M    2376M  6382 570
1019  cfprefsd     0.0  00:00.01 2    2    29   38   240K   220K   920K  
  12M    2378M  1019 1015

This looks fine in the compose window, but will probably be distorted 
when I view it after posting.