Hi Pavan,
Have a look to below mention link
http://scn.sap.com/people/pavan.bayyapu/blog/2005/08/30/sending-html-email-from-sap-crmerp
http://scn.sap.com/people/pavan.bayyapu/blog/2006/08/21/sending-html-email-from-sap-crmerp--2
http://scn.sap.com/docs/DOC-31422
Regards,
Vaibhav Shah