use warnings;
use strict;
use Win32::API;

my $ShellExecute = new Win32::API(
    'shell32',
    'ShellExecuteA',
    [ qw( N P P P P I ) ],
    'N'
);

my $recipient = 'foo@example.com';
my $subject   = 'Hello World';
my $body      = '... funktioniert :)';

$ShellExecute->Call(
    0,
    'open',
    'mailto:' . $recipient . '?subject=' . $subject . '&body=' . $body,
    0,
    0,
    1
);