1. First of all, write: Dear customer, I am very sorry to inform you that our company is going to close down for various reasons. We apologize for any inconvenience caused.

2. Secondly, write: During this period, we will not be able to provide any service and support, and we will clean up the unfinished projects as soon as possible and contact customers for proper handling.

3. Finally: If you have any questions, please feel free to contact our customer service team. Thank you again for your cooperation and support. Sincerely, pay tribute to XXX company.