Thank You Notes
After every interview it is appropriate to send a thank you letter within 48 hours of your interview. It is not necessary for the letter to be long and elaborate. If you feel you should address something you "missed" in the interview, you may do this in your thank you letter.
Employers have different preferences in terms of how they like to receive thank you notes. Some individuals prefer to receive handwritten notes, others typed formal letters or by e-mail. But all generally agree: It is better to receive thank you notes in any form, then not at all.
Address the letter to the person who invited you for the interview initially. If you saw more than one person, you can write to each of them, or refer to them in your letter to the primary interviewer. (Note: Ask for a business card during the interview, this way you can assure you have the right name and address as well as proper spelling.)
Unless you have acquaintance with your interviewer through prior experience (i.e. you have worked for them in the past or met with them on more than one occasion outside of Thayer School), you should address your letter formally. For example, say "Dear Mr. Popascle" instead of "Dear Johnny."
Mention the title of the position for which you have interviewed in your letter. If you are interested in the position, express your enthusiasm and reiterate your desire for the job and your qualifications for it. If possible, add value by referring to a specific aspect of their work that was particularly interesting or appealing to you. (This should be related to the job or the environment, and should not include discussion of salary or benefits.)
If you are not interested in the job, you can still express appreciation for the consideration extended to you. Don't feign affection. It is better to be sincere and simply say thank you for the interview than to add "fluff" that gives the potential employer false expectations about your interest. (Remember that interviewing is a two-way street: Employers are just as nervous about finding good employees as you are about finding a good job.)
To close, if you are interested in the job, express thanks for the interview and the date (specifically or generally) that you expect to hear from the interviewer.
If you are not interested, repeat that you enjoyed talking with the interviewer.