Obviously, your performance during an initial face to face interview will determine whether you are invited back for further discussions. To help increase your chances for a return visit, your work must not stop after the last handshake.
You should mail a follow-up letter within 24 hours of your interview. Ideally, it should be typed (or neatly written) and addressed to the main interviewer or the person to whom you’ll report. The letter should again thank them for their time and consideration and ask for the job! It should portray you as being confident and ready to meet the challenges of the position. By mentioning the other people whom you talked with, it will be obvious that you were attentive, interested in the needs of the employer, and eager to be a member of their team. Another objective of this letter is to demonstrate your writing ability. This letter is an excellent opportunity to recap your problem-solving abilities and make specific mention of major projects or tasks that the company wants to address in this hire and how your strengths can help them achieve their goals.
A written letter is generally preferable to sending e-mail; however, based on time sensitivities, e-mail is acceptable. In the case of e-mail, send the same content as mentioned above to the hiring manager. Also, send a short thank you note to the other interviewers along with any specific comments that you want to include based on your conversations. Address each e-mail individually.

