Determine whether email is the best medium for your message or interaction.
If emailing in a professional relationship, format the email (e.g., use a salutation; include an opening, body, and concluding paragraph; and sign your name) and construct the message accordingly (e.g., use titles when appropriate, such Dr. or Mrs., and use formal language, such as Good morning or Hello instead of Hey).
Use a meaningful subject line that summarizes your message so the recipient knows what your message is about before they begin to read it.
Always review your message for typos and other technical errors. This is your message, and it will say something about you and the relationship you have with the person.
Consider at what time you send the message.
Allow adequate time for a reply, if a reply is needed.
Remember that email is a written record. Even if you delete an email, the other person may not and it is possible that deleted emails will remain on a server for years after you thought you deleted the message.
In some states, all emails on state-owned servers (such as at public universities) are considered public record and can be requested by anyone as part of open records regulations, which are sometimes referred to as “sunshine laws.” If you are unsure of whether you want your words kept “on file” or made public, then consider using the telephone or talking to the person face-to-face instead.
Note that ALL CAPS can be interpreted as screaming, so use it and other formatting possibilities with care.