Question: what are the essential features of a business letter?
Answer: Simplicity: A business letter should be simple. ... 
Conversational style: An effective letter is one that gives an impression of face to face communication. ... 
Clarity of goal: The writer should be clear about what he wishes to convey. ... 
Public relation: ... 
The 'You' attitude: ... 
Courteous: ... 
Persuading: ... 
Sincere: