Simply replace the unfilled areas such as "" and "[date]" with your information.
Dear Valued Customer:
After [number] years of business, we will be closing our doors on [date]. We have enjoyed being a part of this community and we have been happy to serve all of our customers. However, the time has now come for us to explore the other aspects of life.
Beginning (date), everything in our store, including our merchandise, racks, fixtures, showcases, and other equipment will be on sale at extremely discounted, closeout rates. As you have always been a loyal customer, we thought you would like to know about this sale in advance.
We look forward to seeing you and thank you for your patronage,