Here's some pretty basic code for parsing a MIME message,
and outputting its decoded components to a given directory:

use MIME::Parser;

### Create parser, and set some parsing options:
    my $parser = new MIME::Parser;
    $parser->output_under("$ENV{HOME}/mimemail");

### Parse input:
    $entity = $parser->parse(\*STDIN) or die "parse failed\n";

### Take a look at the top-level entity (and any parts it has):
    $entity->dump_skeleton;