If you're one of those people who reckon it's a waste of time to send a follow up letter after an interview, think again. You might just be passing up the chance to score those few extra points that impress a recruiter and swing the hiring decision in your favor.

When you're job hunting in a competitive market, your resume and cover letter need to show that you're a convincing candidate for you to stand a chance of being shortlisted. And when the stakes are high, getting a call for interview is an achievement in itself. That's why it's so important to take every opportunity to create a positive impression -- before, during AND after your interview.

Here are seven compelling reasons why your follow up letter is such a powerful tool:

1. Probably only a few of your rivals have sent one. Everybody makes the effort to prepare thoroughly for the interview itself, but they don't always think about the decision-making process that comes afterwards. Don't let an eager competitor pip you to the post. Be proactive in the way you stay in touch with the employer.

2. You remind the interviewer about yourself. Hiring employees can be a complicated and time-consuming process, particularly when a vacancy attracts a popular response. Don't be just another passing face in the stream of candidates. Sending a follow up letter is a good way to set yourself apart and make another personal connection with the employer.

3. You get a second crack at the whip. Use your letter to mention the skills and experience that mark you out as a great fit for the job. And if there are any details that you forgot or didn't get the chance to bring up at your interview, take the opportunity to state them briefly now.

4. You affirm your interest in the position. What was the high point of your visit? Did a particular part of your interview go really well? Make the most of this chance to build on the goodwill created by a favorable meeting or a positive experience that has increased your enthusiasm for the job.

5. A letter -- or an e-mail -- is a diplomatic way to communicate. If you call the office 'out of the blue', you run the risk of alienating the recruiter by your interruption. Writing a letter or e-mail allows the recipient to take your message when it's convenient and make an appropriate response.

6. You can control when your letter is received. The art of following up effectively depends on good timing. The longer you leave it, the less effective your letter will be in reminding the interviewer about you. Impress the employer with a prompt note that arrives soon enough to influence their decision.

7. It's good manners. And sending a letter isn't just a gesture of courtesy -- it shows that you're thorough and professional in your approach to your job search.

Taking the trouble to contact your interviewer after your meeting is a form of enlightened self-interest that can only add to the favorable impression that's created when an interview goes well. When you thank the employer for having invited you to interview, you show the quality of your 'people skills' and emphasize your assertive and enthusiastic interest in the position you want.