Rename a batch of EML files

eml_renamer.pl

#!/usr/bin/env perl

use strict;
use warnings;

use Email::MIME;
use File::Slurp;
use File::Next;
use DateTime::Format::Flexible;

my $iter = File::Next::files( { file_filter => sub { /\.eml$/ } }, '.' );
while (defined( my $file = $iter->() )) {
    my $text_mail = read_file( $file );
    my $email = Email::MIME->new( $text_mail );
    my $subject = $email->header('Subject');
    my $date = DateTime::Format::Flexible->parse_datetime( $email->header('Date') );

    rename( $file, $date->ymd('-') . ' - ' . $subject . '.eml' );
}