#!/usr/bin/perl
use warnings;
use strict;

use Encode qw{ encode };
use LWP::Simple qw{ get };
use MIME::Parser;

my $parser = 'MIME::Parser'->new;
$parser->extract_uuencode(1);
$parser->extract_nested_messages(1);
$parser->output_to_core(1);

my $email = encode('UTF-8', get('https://pastebin.com/raw/LRs9J4pd'));
open my $f, '<', \$email or die $!;
my $e = $parser->parse($f);

print $e->head->get('Subject');

__END__
Output:
[updates-announce] MGASA-2023-0355: New chromium-browser-stable
 120.0.6099.129 fixes bugs and vulnerabilities