use MIME::Entity;
use Mail::Mailer qw(sendmail); 

my $email = MIME::Entity->build(Type       => "multipart/alternative",
                             To         => 'somebody@example.com',
                             subject    => "Test Email");

$email->attach(Data        => ["THIS IS DIRECTLY ATTACHED TEXT"],
               Type        => "text/plain; charset=UTF-8",
               Encoding    => "quoted-printable");

$email->attach(Data        => ["<h2>THIS IS HTML TEXT<h2>"],
               Type        => "text/html; charset=UTF-8",
               Encoding    => "quoted-printable");

$email->print(\*STDOUT);
$email->send;


##</code><code>##

Content-Type: multipart/alternative; boundary="----------=_1455820701-7549-0"
Content-Transfer-Encoding: binary
MIME-Version: 1.0
X-Mailer: MIME-tools 5.414 (Entity 5.414)
To: somebody@example.com
Subject: Test Email

This is a multi-part message in MIME format...

------------=_1455820701-7549-0
Content-Type: text/plain; charset=UTF-8
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

THIS IS DIRECTLY ATTACHED TEXT=

------------=_1455820701-7549-0
Content-Type: text/html; charset=UTF-8
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

<h2>THIS IS HTML TEXT<h2>=

------------=_1455820701-7549-0--