A professional thank you note should always be sent after an interview, career fair, or information session. A good rule of thumb is if an employer or recruiter went out of their way to meet with you, some form of thanks is appropriate. This can be sent via snail mail or email. Look at this as both a professional courtesy, and an opportunity!
The thank you note gives you the opportunity to do three things. You can express your gratitude for the opportunity to interview for a position and to learn more about the company. You can express your interest once again in a position or in simply maintaining an open line of communication with the employer. And, you can briefly reiterate the skills you possess that would be valuable to the employer. You can do all of these things while providing another example - in addition to your resume and cover letter - of your professionalism and writing ability.
Thank you notes can be delivered in three formats: a standard business letter sent by mail (similar to the formatting in your cover letter); a professional email using appropriate language, good grammar, and correct spelling; or a thank you card with a handwritten message.
Here are a few helpful hints:
Thank you notes are also appropriate for any faculty, staff or contacts who have helped you with the job search process. Thanking people for writing letters of recommendation and/or serving as references is a good habit and speaks volumes about your character and professionalism!