use strict;
use warnings;
use Win32::OLE;
use File::Temp qw/ tempfile tempdir /; 

my $dir = tempdir( CLEANUP => 1 );
my ($fh, $filename) = tempfile( DIR => $dir, SUFFIX=> '.mail' );

my $out = Win32::OLE->new('Outlook.Application') or die "oops\n";

my ($ins, $ai);

if (! (($ai=$out->Application->ActiveInspector) && ($ins=$ai->CurrentItem))) {
	$ins=$out->CreateItem(0);  # 0 = olMailItem
	$ins->Display;
};
print $fh $ins->Body;
close $fh;

system "gvim $filename";

open ($fh, $filename) or die;
local $/=undef;

my $body=<$fh>;
$ins->{Body}=$body;