# slurp the email from STDIN
my( $raw );
{ local $/ = undef; local *FILE; open FILE, "-"; $raw = <FILE>; close FILE }

defined( $raw )
       or die( "Nothing read from STDIN!\n" );

# Create an IO::Handle for Mail::DKIM::Verifier to read message from
my( $raw_iohandle ) = new IO::Scalar( \$raw );

# Read from the IO::Handle
my( $mail ) = load Mail::DKIM::Verifier->new();
$mail->load( \$raw_iohandle );
$mail->CLOSE;

# Import message to Email::Simple
my( $incoming ) = Email::Simple->new( \$raw );