123, X Street, Y Avenue
[Subject: Normally bold, summarizes the intention of the letter] -Optional-
Dear Austin Parker,
A sincere congratulations on the fifteenth anniversary of Lane’s Grill Restaurant. We have been consistent diners at your restaurant, and through all these years we can say that you offer the best food and service in town, and these have brought you much success. We believe that your restaurant is more than just an outstanding dining establishment. The business community deems it a perfect gathering place.
We are so pleased with doing business with you, and we give you our warmest wishes to your continuing success.