This is the code form my small test script:

#! /usr/bin/perl

use strict;
use warnings;
use Mail::DKIM::Verifier;

my $raw_email;
my $dkim = Mail::DKIM::Verifier->new();

open (MESSAGE, "< $ARGV[0]") || die "Couldn't open email $ARGV[0]\n";
       undef $/;
$raw_email = <>;
close MESSAGE;

print "$ARGV";

open(my $fh, "<", "$ARGV") or die "Can't open < $ARGV: $!";
$dkim->load($fh);

my $result = $dkim->result;
print "\n$result";

foreach my $signature ($dkim->signatures)
  {
      print "signature identity: " . $signature->identity . "\n";
      print "verify result: " . $signature->result_detail . "\n";
  }
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I have tested this script with differed emails. Test files with correct, wrong and missing DKIM signature. The script returns always "none" (my $result = $dkim->result;) and $signature is an empty variable.

It seams that this script canīt find a DKIM signature in the test files.

open (MESSAGE, "< $ARGV[0]") || die "Couldn't open email $ARGV[0]\n";
       undef $/;
$raw_email = <>;
close MESSAGE;
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Hello, nifu. Could you please explain what this section of code is doing and why?

I use this to open the file and parse it with the module Email::Simple;.

This is the code from my "email parse script". I need to extend this script with a DKIM check.

#! /usr/bin/perl

use strict;
use warnings;
use Email::Simple;
use DBI;
use File::Copy;
use Date::Parse;
use DateTime;
use Path::Tiny qw(path);

[..]

open (MESSAGE, "< $ARGV[0]") || die "Couldn't open email $ARGV[0]\n";
       undef $/;
$raw_email = <>;
close MESSAGE;

my $mail            = Email::Simple->new($raw_email);
my $from_header     = $mail->header("From");
my $to_header       = $mail->header("To");
my $date_header     = $mail->header("Date");
my $aol_header      = $mail->header("Authentication-Results");

[...]
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$ARGV is the filename form perl script.pl filename and $raw_email contains the text file.