Dear (insert contact’s last name)
Paragraph 1: Here you should indicate that you have been asked to contact the reader to provide proof that you were the employer of the person who is requesting work from your reader. In this paragraph you will be required to indicate their starting date, their leaving date, the positions they held whilst under your employment and what their general duties were in this position.
Paragraph 2: Depending on what has been requested of you by your previous employee, you should indicate here on how you viewed their performance in the job. It is important for this part of the letter to be positive, so you can mention positives, and leave out any negative comments.