Email etiquette
Everything You Need to Know About Office Email Etiquette
https://www.youtube.com/watch?v=Dl6Hsw7ojYs
Correct Tone in Email - From The IT Crowd's first season ("Calamity Jen"): a consideration of planning, writing, and completing an effective business email communication.
https://www.youtube.com/watch?v=8y4xifEt7X8
Other YouTube videos: E-mail etiquette by kimkomandoshow