Learn how to write an employee appreciation letter with these templates and examples. Download the template for free (PDF or Word).Sending out customer appreciation letters is an excellent way to connect with your clients. Learn how to write a customer appreciation letter here. I want to congratulate you personally for completing your year with < company name >. It has been a pleasure working with you. The message of appreciation should stand alone. Be brief, warm, and sincere. Improve your customer service with Customer Appreciation Letters. We share tips for good service and how to reply to customer emails.