I got this directly from a recruiter friend, and it outlines all the most basic things about these notes. Good stuff!

Below are a few tips on writing formal thank you and follow-up letters to employers:

Thank you letters should be sent within 24 hours of attending the job interview. This will ensure the employer will remember and associate the letter with the interview and will certainly appreciate the effort

• Employer Details: Addressing the letter to the relevant person and typing all information pertaining to name, designation, and location should not have any mistakes. An error-free thank you letter will indicate one’s attention to detail among other things.

• Express Enthusiasm: Express your interest and genuine thanks to the employer by indicating you value the organization and the time they spent talking to you. Use this opportunity to mention you look forward to associating with their team and learning and contributing to their organization.

• Address Unresolved Issues: A brief line or two seeking clarification regarding any doubts you might have after the interview can be included in the thank you letter. Since the thank you letter is perhaps the last chance to indicate or confirm terms, this request must be drafted carefully and must leave a positive impact.

• Personalize not Dramatize: While it is important to personalize the letter a little in an effort to not make it sound too vague and common, one must certainly not go overboard and dramatize the letter. Clearly express your appreciation and interest in the culture of the organization and indicate how informative and interesting it was talking with the employer.

• Conclusion: This should be brief and mention that you look forward to hearing from the employer, and are available by phone or email for any clarifications, or if they require you to attend another round of discussion or interview. Since email is the most commonly used medium of communication, both thank you and follow up letters can be sent via email, if you know the recipient reads their email regularly.

This is better compared to snail mail via the post office, and it is even more important to send the letter in time to employers after attending interviews!