Interviewing - Successful Selectionby Jane Tredgett
Always advise candidates of the outcome, whether they were successful or not. Ideally, do not leave this for more than a week after the interview, out of courtesy for the candidate.
Make sure your letters are short, factual and non-judgmental. Aim to leave a positive impression, even if you are turning a candidate down. See Screening applications for more information on rejection letters.
If unsuccessful applicants ask for more specific feedback, try to be honest, but couch any feedback politely (instead of saying they looked a mess, it might be more diplomatic to say something how their appearance might impact on customer impressions).
If the candidate is successful, you may wish to let them know by telephone first, and then follow up with a letter. Ensure you advise them fully as to what happens next.