use MIME::Lite;
my $msg = MIME::Lite->new(
            From        => 'from',
            Reply-To    => 'replyto',
            To          => 'email',
            'Errors-To:' => 'errors',
            Subject     => 'Errors to header',
            Data        => 'Add a :'
       );
print $msg->as_string;

__DATA__
Content-Disposition: inline
Content-Length: 7
Content-Transfer-Encoding: binary
Content-Type: text/plain
MIME-Version: 1.0
X-Mailer: MIME::Lite 3.01 (F2.6; B2.12; Q2.03)
Date: Thu, 15 Apr 2004 12:56:05 UT
From: from
To: email
Errors-To: errors
Subject: Errors to header

Add a :