sending html with python and outlook

I am trying to test sending an html table in the body of an outlook email, using ntlm, urllib2 and some other stuff. I can send email text successfully, but not html. Please have a look at my code and see if you can spot the error. Thanks very much!

import urllib2
from ntlm import ntlm
from ntlm import HTTPNtlmAuthHandler
import urllib2
from urllib2 import URLError
from datetime import *
from html import HTML
import smtplib

h = HTML()
t = h.table(border='1')
for i in range(2):
   r = t.tr
   r.td('column 1')
   r.td('column 2')

h=str(h)

url = "https://corporateemail..."


passman = urllib2.HTTPPasswordMgrWithDefaultRealm()
passman.add_password(None, url, user, password)

#create NTLM authentication handler
auth_NTLM = HTTPNtlmAuthHandler.HTTPNtlmAuthHandler(passman)

#create and install the opener
opener = urllib2.build_opener(auth_NTLM)
urllib2.install_opener(opener)

xml = '''<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"
  xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types">
  <soap:Body>
    <CreateItem MessageDisposition="SendAndSaveCopy" xmlns="http://schemas.microsoft.com/exchange/services/2006/messages">
      <SavedItemFolderId>
        <t:DistinguishedFolderId Id="drafts" />
      </SavedItemFolderId>
      <Items>
        <t:Message>
          <t:ItemClass>IPM.Note</t:ItemClass>
          <t:Subject>Testing Email</t:Subject>
          <t:Body BodyType="HTML">%s</t:Body>
          <t:ToRecipients>
            <t:Mailbox>
              <t:EmailAddress>[email protected]</t:EmailAddress>
            </t:Mailbox>
          </t:ToRecipients>
          <t:IsRead>false</t:IsRead>
        </t:Message>
      </Items>
    </CreateItem>
  </soap:Body>
</soap:Envelope>''' % h

req = urllib2.Request(url=url, data=xml, headers={'content-type': 'html/xml'})

response = urllib2.urlopen(req)