Anyone who uses e-mail on the job has gotten one: an e-mail that’s unprofessional, curt, or worse, borders on rude. Most of us who use e-mail as a way to communicate in the corporate world know to keep it brief and professional. But without face-to-face contact, e-mails can be easily misunderstood.

Why do some people let it all hang out in their e-mail communication – the good, bad and the ugly? According to Dr. Jack O’Regan, dean of the College of Psychology and Behavioral Sciences at Argosy University, there’s an actual psychological effect behind this phenomenon.

“We all make various decisions in our daily lives and most are done with some level of governance,” said Dr. O’Regan. “The issue people face is really a ‘disinhibition effect’ where, due to the interpersonal nature of e-mail, the user often does not use the same levels of governance on appropriateness that you would have in other forms of communications.”

In today’s “e-mail culture,” people are so used to “interacting through e-mail messages in a certain way that many don’t think of it as unprofessional and they are often very upfront and in your face,” he added.

“Since humans communicate a huge amount of information non-verbally, using sarcasm or humor in an e-mail can be easily misinterpreted,” according to Chad Ness, director of technology and facilities for The Art Institutes International Minnesota.

Ness said in social e-mails, when people joke, or use sarcasm, they may use a graphic or icon – like a smiley face – to indicate a wink or a nod. But in corporate e-mail communication, smiley faces are frowned upon, so those visual nuances aren’t as easily communicated.

A good rule of thumb, Ness said, is don’t say in an e-mail what you wouldn’t say to someone in person.

“Absolutely avoid anything offensive, racist, libelous, or defamatory,” he said. It may seem obvious, but “the courts are full of case histories of companies that have paid out huge penalties because of one person’s thoughtless moment.”

Ness has a few easy guidelines for keeping business e-mails the professional, courteous and timesaving tool they are intended to be.

Generally, send an e-mail when you want to communicate information to large numbers of people, when you want a written record or you can’t reach someone on the phone and don’t want to tie-up a voice mail machine with a long message.

On the flip side, Ness said, you should avoid e-mail when you need an immediate reply, the conversation will require a lot of back and forth, or the conversation should be kept private.

Other do’s and don’ts for e-mail in the corporate world include:

• Use a good subject line. Make sure it contains clear information about what you are communicating.

• Make your e-mails as short and to the point as possible.

• Be sure to reply to an e-mail as soon as possible. In this day and age 24 hours is the longest any e-mail should sit.

• Avoid forwarding other people’s discussions or attachments without their specific permission.

• E-mail is generally not a secure medium, so company confidential information should generally not be sent over the Internet.

• Don’t type in all capital letters.

• Save the “cc” feature for when there’s an important internal communication that must get to everyone.

• Don’t mark your e-mail as “Urgent,” unless it is truly important.