Hi Anshul,
Please go to the
Class - > /SAPPSSRM/CL_TNDR_MAIL and put a break point in method SEND_MAIL as shown
check the lo_badi_mail ( it should not be INITIAL ) and the Exporting Parameter iv_object_id ( In Most Cases it remains blank ) and implement your code accordingly.
Hope this will resolve your issue.
Regards
P K Surya