Your cover letter should highlight your successes from past positions. Writing a cover letter for a previous employer requires highlighting your existing knowledge, valuable skills, and showcasing how you've grown since leaving.I am writing to apply for a Juvenile Probation officer position in your office. My internship with your office in the summer of 2004 prompts my interest. We'll tell you why you might be asked to reapply for your current job and how you can succeed. Plus we've provided some sample cover letters to use. "Hello, I'm a former employer of ABC and I'm very interested in the job of production manager that you have advertised. In this guide, we share 11 different short cover letter samples to ponder. Some of the best slogans are just a few words. "Hello, I'm a former employer of ABC and I'm very interested in the job of production manager that you have advertised.