1. State the purpose of the letter right away
You don't want long introductions and distracting stories. In the first two to four sentences, be clear and concise about the purpose of your letter.
Ideally, it should be stated in one sentence: "Please provide me with a fake passport," "I'm sorry, but there is no way to give you a raise right now," "I suggest that you stop decorating the walls of the office elevator with poison ivy as soon as possible."
Argue and offer solutions
Business correspondence can drag on because of endless clarifications and explanatory accompaniments. Make sure right away that the recipient understands why the solutions you propose are important. For every affirmative sentence you write ("We'll hold the annual shareholder meeting in parallel with the children's party this time"), ask yourself "why?" in your mind and answer it in the letter ("Because the chairman is bad at remembering faces anyway, and we'll tell the kids that they are pokemons").
Gather statistics, analytics, and real-world examples in advance that make your point, and boldly offer a possible solution based on them. Now, if the addressee accepts it, it will turn out that he followed world trends, and not your (possibly unprofessional) advice: "This year we will be able to expand our production of pressed accordions, because, according to world statistics, the music market is growing.
3. Demonstrate that you read the correspondence carefully
If you answer a detailed 19-paragraph letter with a curt "yes," it may be construed as an attempt to get away from your conversation partner. Ideally, your response should be commensurate with the letter you read.
You don't need to count the letters, just appeal to the original text: "You are asking if we will pay attention to the problem of job shortages. This is a complex issue, and we will begin to address it as soon as we downsize the planning department."
4. Adjust to the recipient's style
People perceive the world around them in different ways. Some rely more on their ears, some on their eyesight or senses. In writing, it's easy to tell by phrases like "I'm observing the state of your tech," or "I came across an unusual website on the web."
You may be adjusting to your opponent by deliberately copying his or her sensory model. Does your interlocutor misuse "visual" verbs? Respond, "Glad you're willing to broaden your horizons. Believe me, our collection of voodoo dolls is pleasing to the eye." Tune in on a tactile wave - "Your question concerns us all. We'll get right on it today."