Simply replace the unfilled areas such as "" and "[date]" with your information.
Enclosed please find [number of copies] copies of the [type of material] that you ordered. Also enclosed is a copy of the proof sheet which was signed by [name of proof approver] with your office.
As all work has now been signed off on, and all ordered copies have been provided, we are also including an invoice for payment. The total amount due is [amount due]. Per our agreement, payment terms are thirty days net. We would appreciate if you would put this invoice in line for payment.
Please let us know if you have any questions, or if there are any issues with the material being provided.
Thank you for the opportunity to serve you. We look forward to working with you again in the future.