Email is one of the most convenient ways to be impetuously stupid, so if you are writing an email you wouldn't want your boss to read — or the SEC, or your grandma — then don't send it.
Assume that everything you write via email will appear in the business section of the newspaper. Compose your messages with care and pause before you send; ask yourself, “Does this email make me look good?” Obviously, if you are about to lie or cheat, do not send an email to document your lack of ethics. But there are some other, less obvious types of email which won't make you a felon, but they won't make you look good, either, so don't send them.
1. The you're-a-screw-up email
If you need to tell someone they did a bad job, do it in person so you can gauge their reaction. For example, if you open with “Your negligence on this project cost the department $2 million,” and then the employee starts crying, you probably shouldn't continue in an extremely angry tone — at least not until he composes himself. Another reason not to reprimand via email: people will leave this type of email in their in-box for weeks and weeks and reread it every time they want to resurrect their hate for you. Talking in person helps everyone to move past the conflict without sour residue.
2. The I'm-a-screw-up email
Do not document your weaknesses. If you must apologize for botching a project, do it in person so there is no email record of your mistake for people to forward around the office. The more documentation you leave, the more your mistake festers in peoples' minds. And for God's sake, do not send a mass email to apologize. You will invariably announce your screw-up to people who would never have heard of it otherwise.
3. The bcc email
This email function is for people who are insecure, manipulative, and undermining of their co-workers. Even if you are this type of person, do not announce it to everyone by using the bcc function. Sure, only the people in the bcc line realize you're using it. But all those people will understand that you are not strong enough to let everyone know who's reading the email. If you feel compelled to use the bcc function, ask yourself why. Then get up off your chair, go deal with the problem face-to-face, and then go back to your desk to send a more honest email.
4. The joke email
Even if it's the funniest joke of all time (which I am sure it isn't) do not send it to your co-workers. Why make the announcement that you read spam during work hours? You should be working. You might think that telling a joke is a good way to establish rapport, but a spam joke is unoriginal, and impersonal and does nothing to make you closer to co-workers who matter. Besides, if someone thinks the joke is stupid, she will think you are stupid for sending it.
5. The Dear John email
I am amazed at how many people break up via email, from the office. I realize that some people are such dirt bags that they don't deserve a nice breakup. I also realize that if you handle a breakup from your office then the pressures of work can distract you from the drama of your personal life. But I am sure that there will be a web site — maybe a new section on Match.com — for people to publish breakup emails received. And your name will be mud in the dating world if you are known for sending breakup emails from work.
The bottom line is that sending an email is like getting dressed in the morning — both are ways to manage the way people perceive you. The only difference is that if you have a terrible outfit, you can take it off and never wear it again. A terrible email propagates in cyberspace and will seem, to the original sender, to last forever.