Anything you send over the internet is forever recorded on the world wide web. Email is no exception. While email might seem like a casual method of communicating, you should be careful of what you are sending and to whom you are sending it.
Do not send jokes, chain letters, or suspicious emails to business associates. Double and triple check emails before sending. Because email lacks any tone, its imperative that whatever you send out be error free in order to avoid any misunderstandings. Avoid using all CAPS throughout an email as it can be misconstrued as yelling.
When composing an email get to the point as quickly as possible and likewise, people expect prompt responses. If you are someone who only checks email once a week, let people know that so they can plan on it.