Not only does this mean that you should focus on neutrality in your letter’s appearance (avoiding the use of colorful paper, brash logo designs, and artistic fonts), but it also means that you should employ a very low_key, unnuanced, and professional closing phrase. The best_case scenario is that the hiring manager, colleague, or connection won't even notice the closing.
Letter Text: Business letter text should be clean and readable. Avoid writing your letter in one large block of text. Break your text into several concise paragraphs. These paragraphs should be aligned to the left; this allows for easier reading. When you have completed your letter, ask someone else to read it for you. Have them glance briefly at the letter. Is there too much text on the page? Is it easy to see the distinct paragraphs?