Hi Imran,
To achieve this functionality, you can either use FORK step with 3 parallel and 3 necessary branches. In each of the branch of fork, use send mail step with the desired format.
Also, instead of using standard SEND MAIL step, you can simply create 3 standard texts in SO10 and then create a method in Business Object where in based on your conditions you can read the respective texts. And then call the class or function module to send the email with that text.
Also, you can export the read text to workflow and then use this text inside SEND MAIL step.
Richa