Answer:
opening, body, close
Step-by-step explanation:
Opening:
This part will consist of your general introduction. You will tell the receiver of the message about who you are along with the reason you choose him/her for the message.
Body:
This contains the core of your business messages. It might include your business proposals or some sort of rearrangement for a certain cooperative effort.
Close:
This part will be filled with conclusion. It is also very advisable to thank the receiver for his/her time along with a signature for background check purpose.