Redundant multipart

Hello!

If I send the following e-mail to RT:

Subject: =?koi8-r?B?1MXT1A==?=
Message-ID: 20030611160509.GA70999@fling-wing.demos.su
Mime-Version: 1.0
Content-Type: text/plain; charset=koi8-r
Content-Disposition: inline
Content-Transfer-Encoding: 8bit

О©╫О©╫О©╫О©╫

it is resend by RT as

X-Mailer: Perl5 Mail::Internet v1.58
Sender: World Wide Web Owner www@vh.demos.su
RT-Attach-Message: yes
RT-Ticket: vh.demos.su #682
Message-Id: rt-3.0.3pre3-682-805.7.41722022066277@demos.su
Precedence: bulk
Reply-To: info@vh.demos.su
Content-Type: multipart/mixed; boundary="----------=_1055347514-1031-4"
X-RT-Loop-Prevention: vh.demos.su
To: info@vh.demos.su
X-RT-Original-Encoding: utf-8
RT-Originator: mitya@demos.su
From: mitya@demos.su
Date: Wed, 11 Jun 2003 20:05:14 +0400 (MSD)

This is a multi-part message in MIME format…

------------=_1055347514-1031-4
Content-Type: text/plain; charset=“koi8-r”

О©╫О©╫О©╫О©╫

------------=_1055347514-1031-4–

It is clear that multipart/mixed is not needed is such a case.
Is it possible to avoid making unnecessary multiparts?

Thanks!