I will now assume that your mail is sitting in a text file named incoming.

#!/usr/bin/perl -w
use strict;
use MIME::Parser;

my $parser=new MIME::Parser;
$parser->output_dir("mime");
open FILE, "incoming" ||die "could not open\n";
my $email=$parser->read(\*FILE)||die "could not parse\n";
close FILE;
## Now $email is a MIME::Entity.
if (!$email->parts) {
  my $bodyh=$email->bodyhandle;
  my $IO = $body->open("r") || die "open body: $!";
  open OUTFILE, ">body";
  while(defined($_ = $IO->getline)) {
    print OUTFILE;
  }
  $IO->close;
  close OUTFILE;
} else {
  print "This is a multipart MIME message, and I need to do more work 
+to be able to read it.\n";
}
$email->purge;
[download]

Hopefully that gets you started... No guarantees against typos in the code...

# taken from perldoc Mail::POP3Client...

       use Mail::POP3Client;
       $pop = new Mail::POP3Client( USER     => "me",
                                    PASSWORD => "mypassword",
                                    HOST     => "pop3.do.main" );
       for( $i = 1; $i <= $pop->Count(); $i++ ) {
         foreach( $pop->Head( $i ) ) {
           /^(From|Subject):\s+/i && print $_, "\n";
         }
       }
[download]

open FILE, "filename" or die "no file! $!";
print FILE $pop -> Body( $i );
close FILE or warn "$!";
[download]

--
Laziness, Impatience, Hubris, and Generosity.