From the book How to Prepare for an Employment Interview.
Get the entire book by e-mail in Microsoft Word format.
After the interview is over, the last thing [the interviewers] want is to receive a letter from an interviewee. The interviewer didn't do you any favors by granting you an interview. He was acting out of selfish motives, so you do not have an obligation to "thank" him.
- Anthony Medley, Sweaty Palms
Each evening you MUST take time to sit down and write a brief thank-you not to each person that you saw that day. That includes secretaries, receptionists, or anyone else.
- Richard Bolles, What Color is Your Parachute?
See addendum here
The question of what you should do after the interview always evokes a vigorous debate between those who think you should immediately send a "thank-you" note (like Bolles) and others who insist that such an approach may even be harmful (like Medley).
From what I've read, the majority side with Bolles. But I'm much more sympathetic to Medley's views. This is a very divisive issue. Stan Wynett, author of Cover Letters That Will Get You the Job You Want, and a person I usually agree with, takes the opposite view. He feels that "you become a member of the privileged class the moment the employer decides to take a chance on you by inviting in for a face-to-face interview. You have survived the first cut and an expression of gratitude is in order."
I disagree. The employer's motivation for interviewing you is purely out of self-interest. As I've tried to make clear, they don't care about you, they care about solving their problems. They wouldn't be interested in you at all if they didn't think you might be worth more to them than you'll cost.
You didn't survive the first cut through of an act of kindness. You made it because you persuaded the employer that you might offer them something of value... [Continued here]