Hi Ramesh
Just for emails.....try not to over engineer with workflows!
Try to find an enhancement where you can send an email via the methods of class CL_BCS... No workflows required, No troubleshooting in that area ... no maintenence in future for workflows....JUST FOR AN EMAIL!
If you still want to stick to WF, you can follow what Abhijeet has mentioned above.
Regards,
Modak