Opening Part: The first paragraph of the mail writing must state the introduction of the writer. It also contains the previous correspondence if any. Main Part: This paragraph states the main idea or the reason for writing. It must be clear, concise, complete, and to the point. Concluding Part: It is the conclusion of the business letter. It shows the suggestions or the need of the action. The closing of the letter shows the expectation of the sender from the recipient. Always end your mail by courteous words like thanking you, warm regards, look forward to hearing from your side etc.
Letter Paragraphs: Professional letter paragraphs should be relatively concise. The first paragraph may include a brief friendly opening and a concise explanation of your reason for writing. The second paragraph (and any subsequent paragraphs) should expand upon your reason for writing. The final paragraph should restate your reason for writing and, if applicable, state your plan of action (or request some type of action be taken by the reader).