How do you know for sure whether or not to use a closing? One good test is to ask yourself whether this email is more akin to an instant message/text or a business letter. If you're giving your teammate a quick update on an ongoing project, a formal closing might not be necessary; if you're throwing your hat in the ring for a promotion, it definitely is required. When all else fails, and you're still not sure, err on the side of caution and include it. You'll never go wrong by being too polite and respectful.
Font Size: The traditional font size for a professional letter is 12. The font should be Times New Roman or Arial. However, if you are using letterhead, the letterhead may be in different font size and style. Font Style: There is no need to use different styles within a professional letter. Use a uniform font (book print font such as Times New Roman or Arial) and avoid underlining, italicizing, or bolding. However, if you are using letterhead, the letterhead may be in a different font style.