Most of us rely on e-mail as one of our primary communication tools. And given the number of messages we send and receive, we do it with remarkable success. But as with anything, the more e-mails we send, the more likely we are to screw one up. And simple e-mail mistakes can be disastrous. They can cost us a raise, promotion--even a job. With a new year upon us, this is the perfect time to go through some of the worst e-mail mistakes employees make and how to avoid them. 1. Sending before you mean to. Enter the recipient's e-mail address only when your e-mail is ready to be sent. This helps reduce the risk of an embarrassing misfire, such as sending an important e-mail to the wrong person or e-mailing a half-written note. [See 9 Little-Known Ways to Damage Your Reputation at Work.] 2. Forgetting the attachment. If your e-mail includes an attachment, upload the file to the e-mail beforecomposing it. This eliminates the embarrassing mistake of forgetting it before hitting "send," and having to send another e-mail saying you forgot to attach the document. 3. Expecting an instant response. Don't send an e-mail and show up at the recipient's desk 30 seconds later asking if they've received it. They did, and they'll answer at their convenience. That's the point of e-mail. 4. Forwarding useless e-mails. I've never seen a single e-mail forward at work that was beneficial. Whether it's a silly joke or a heartwarming charity, there's never a time to share an e-mail forward using your work e-mail. 5. Not reviewing all new messages before replying. When you return to the office after a week or more away, review all new e-mails before firing off responses. It might be hard to accept, but odds are, things did march on without you. Replying to something that was already handled by a co-worker creates extra communication, which can lead to confusion, errors, and at the very least, wasted time for everyone involved. 6. Omitting recipients when you "reply all." Unless there's an important reason to omit someone, don't arbitrarily leave people off the response if they were included on the original message. 7. Including your e-mail signature again and again. Nor do you need to include it at the end of an e-mail you send to your long-time co-worker who sits six feet away. If you have your e-mail program set to automatically generate a signature with each new message, take a second to delete it when communicating with someone who knows who you are. It's always wise to include your phone number, but the entire blurb with your title and mailing address is often nothing but clutter. 8. Composing the note too quickly. Don't be careless; write every e-mail as if it will be read at Saint Peter's Square during the blessing of a new Pope. Be respectful with your words and take pride in every communication. 9. Violating your company's e-mail policy. Many companies have aggressive spam filters in place that monitor "blue" language. From that famous four-letter word to simple terms, such as "job search," don't end up tripping the system by letting your guard down. 10. Failing to include basic greetings. Simple pleasantries do the trick. Say "hi" at the start of the message and "thanks" at the end. Be sure to use the recipient's name. Be polite yet brief with your courtesy. 11. E-mailing when you're angry. Don't do it. Ever. Recall buttons are far from a perfect science, and sending a business e-mail tainted by emotion is often a catastrophic mistake. It sounds cliche, but sleep on it. Save the message as a draft and see if you still want to send it the next morning. 12. Underestimating the importance of the subject line. The subject line is your headline. Make it interesting, and you'll increase the odds of getting the recipient's attention. Our inboxes are cluttered; you need to be creative and direct to help the recipient cut through the noise. You should consistently use meaningful and descriptive subject lines. This will help your colleagues determine what you're writing about and build your "inbox street cred," which means important messages are more likely to be read. 13. Using incorrect subject lines. Change the subject line if you're changing the topic of conversation. Better yet, start a new e-mail thread. 14. Sending the wrong attachment. If you double-check an attachment immediately before sending and decide that you need to make changes, don't forget to update the source file. Making corrections to the version that's attached to the e-mail does not often work, and it can lead to different versions of the same doc floating around. 15. Not putting an e-mail in context. Even if you were talking to someone an hour ago about something, remind them in the e-mail why you're writing. In this multi-tasking world of ours, it's easy for even the sharpest minds to forget what's going on. 16. Using BCC too often. Use BCC (blind carbon copy) sparingly. Even though it's supposed to be a secret, it rarely is. Burn someone once, and they'll never trust you again. Likewise, forwarding e-mail is a great way todestroy your credibility. When people send you something, they aren't expecting you to pass it on to your co-workers. The e-mail might make its way back to the sender, who will see that their original message was shared. They might not call you out on it, but they'll make a mental note that you can't be trusted. 17. Relying too much on e-mail. News flash! No one is sitting around staring at their inbox waiting for your e-mail. If something is urgent, use another means of communication. A red "rush" exclamation point doesn't compare to getting up from your desk and conducting business in person. 18. Hitting "reply all" unintentionally. This is a biggie. And it's not just embarrassing; depending on what you wrote in that e-mail, it can ruin your relationship with a co-worker or even your boss. Take extra care whenever you respond so you don't hit this fatal button. Now it's time to fess up: Are you guilty of any of these common work e-mail mistakes? Any you'd like to add to the list?