If you're going to be sending html emails you might want to consider reading up on mime encoding. Here's a sample message that contains a plain text section and an html section. Just make sure your boundry tag is something that would never occur in the text of either message.
-------------------------------------------------------------
Date: Mon, 29 Apr 2002 19:29:36 EDT
Subject: testing
To:
[email protected]
From:
[email protected]
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="part1_123456789.987654321_boundary"
--part1_123456789.987654321_boundary
Content-Type: text/plain; charset="US-ASCII"
Content-Transfer-Encoding: 7bit
This is the plain text message
--part1_123456789.987654321_boundary
Content-Type: text/html; charset="US-ASCII"
Content-Transfer-Encoding: 7bit
<HTML>
<H1>This is the HTML message</H1>
</HTML>
--part1_123456789.987654321_boundary--