Hi,
Have you tried sending an email using CL_BCS or CL_DOCUMENT_BCS way?
Class CL_BCS: http://help.sap.com/saphelp_sm32/helpdata/en/2d/1c5d3aebba4c38e10000000a114084/content.htm
Class CL_DOCUMENT_BCS: http://help.sap.com/saphelp_NW70EHP1core/helpdata/en/8c/5bf13b68402b69e10000000a11402f/content.htm