Receiver mail adapter attachment and body issue

Hi I'm trying to implement the scenario described in the blog below in SAP PI 7.31 single stack system however I'm facing issues the below issues any help is highly appreciated.

http://scn.sap.com/people/samuel.chandrasekaran2/blog/2008/10/06/xi-mail-adapter-dynamically-building-attachment-and-message-body-content-using-a-simple-udf#comment-435490

the output of mail package mapping mapping is as follows:

<?xml version="1.0" encoding="UTF-8"?>

<ns1:Mail xmlns:ns1="http://sap.com/xi/XI/Mail/30">

   <Subject>Mail Excel attachment package</Subject>

   <From>bhargav.gundabolu@test.com</From>

   <To>bhargav.gundabolu@test.com;</To>

   <Content_Type>multipart/mixed; boundary=--AaZz</Content_Type>

<Content><![CDATA[----AaZz Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline  Hi, This ia a test email. ----AaZz Content-Type: application/xml; name=Invoice.txt Content-Disposition: attachment; filename=Invoice.txt  test email ]]></Content>

</ns1:Mail>

This contains all the required information. However this is not working any thoughts? the emai does not contain any body or an attachment.