are you sure that you send a right formatted HTML mail...
have you set the MIME-Version? here is an sample of a well formed MIME HTML mail: 
Subject: Some Subject
Date: Wed, 17 Dec 2003 12:26:50 +0100
Message-ID: <E1E811923F2F054DB62E330FE5B3720544D7A7@sub.host.dom>
From: "Body, Some" <some.body@host.dom>
To: "Body, Any" <any.body@host.dom>
MIME-Version: 1.0
Content-Type: text/html;
    charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
<HTML>
<HEAD>
<META HTTP-EQUIV=3D"Content-Type" CONTENT=3D"text/html; =
charset=3Diso-8859-1">
<TITLE></TITLE>
</HEAD>
<BODY>

<P><FONT SIZE=3D2 FACE=3D"Arial">This is a Test.</FONT>
</P>

<P><FONT SIZE=3D2 FACE=3D"Arial">Bye,</FONT>

<BR><FONT SIZE=3D2 FACE=3D"Arial">Some Body</FONT>
</P>

</BODY>
</HTML>

[download]
Have fun! :)

In reply to Re: Send HTML mail to Outlook by esskar
in thread Send HTML mail to Outlook by cosmicsoup

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.