It is an interesting request. I may experiment
with it myself.
I did it: I changed mhexternal.pl so it can recognize the new option
'icon', and puts an icon in the message for the attachment. I can mail it
to anyone interested, but ofcourse it's quite experimental. You can see it
at <http://thorin.pds.it/network/archivi/network/msg00241.html> (it's
Italian, but it's irrelevant).
I did experiment for myself, and the next release of MHonArc will have
a changed mhexternal.pl that can insert icons. It can use what is
specified by the ICONS resource, or you can explicitly specify icons to