BEFORE you send that "cute" remark, that scathing criticism or that "private" thought via e-mail, stop and consider what you are really saying.
Even Tina, the tech writer in the Dilbert comic strip by Scott Adams, says: "One should never compose e-mail while one is snarling."
How you feel affects what you say, of course, but with e-mail, there is a even greater danger than offending someone.
As an e-mail writer, you should think about what would happen if other people had your e-mail records - because they may be able to retrieve them.
While e-mail is a simple and fantastic way to keep in touch with friends and business associates, it also has some security and legal problems attached to it.
In an effort to remove potential security problems with e-mail, Amazon.com initiated a Sweep And Keep programme. Staff were encouraged to purge e-mail messages that need not be kept for legal records. As a reward for deleting e-mail messages quickly, the employees were treated to free lattes.
Writing for the Cox News Service, Ms Mary Beth Regan says that many people compose e-mail messages personally and candidly because they assume no one but their friends will read them.
She adds: "But unlike telephone conversations, which must be recorded to be preserved, e-mail messages automatically live on in computer hard drives - even if people who send them don't realise it.
"For that reason, investigators are turning more frequently to retrieved e-mail as evidence in court proceedings."
Under the United States federal law, first-class letters, telephone conversations and e-mail messages cannot be intercepted - without a court order - during transmission.
A phone call - unless it is recorded - ceases to exist the instant a conversation is over. That is not true with e-mail messages. E-mail messages are stored, and not just in one place.
If you send an e-mail message, it will be stored on your computer's hard drive, the recipient's hard drive, possibly on an in-house server's hard drive and possibly on the hard drive of an Internet service provider (ISP).
At the least, there are four different places from which an e-mail message could come back to haunt you. If under a court order, commercial ISPs are required to turn over messages for investigation.
Recently, I had to re-install the Windows operating system on my computer. It was done at a computer shop.
When I set up the computer again at home, I was astounded to find that my saved e-mail messages had been replaced by e-mail messages that I had deleted over a year before.
I was dismayed that I had to delete them again, but I was happy that there was nothing embarrassing for the computer repair people to read and nothing that could be used against me in a court of law.
E-mail just lives on and on and on.
Mr James Dempsey, senior staff counsel at the Center for Democracy and Technology in Washington, DC, says: "People are using e-mail as a substitute for telephone calls...But they are also creating records that are being used in civil and criminal proceedings."
Adds Mr Paul Heylman, an employment law attorney based in Washington, DC: "E-mail is informal, so managers often say things that would never go in a memo.
"E-mail (often recoverable after deletion) is often as potent as a formal memo."
Mr Tom Blanton, director of the non-profit National Security Archive at George Washington University, says: "The scary thing about e-mail is that it's got the immediacy of a conversation but the permanence of a letter...Generally, you don't want to write anything you wouldn't want to see on the front page."
So, before you send that off-hand remark over the Internet or your company's Intranet, stop and think it over. Maybe a phone call would be better - and safer.
E-mail can prove embarrassing, can involve lawsuits and can harm other people. That is the hard truth about an easy-to-use communication tool.