The way you communicate in your emails reflects the type of person you are: your professionalism, work ethic and attention to detail. Writing clear professional emails minimizes the chance for misunderstandings and conveys an image of competence.
Keep fonts, sizes and colour simple. Arial, Calibri or Times New Roman fonts in black 10 - 12 point. No matter which font style you choose, be consistent throughout your messages in both style and size. Switching between styles and sizes is jarring for readers.
Proofread before sending. This tends to be a step that many people skip, and can cause unnecessary miscommunication. Check your spelling, grammar, punctuation and that your message is clear.