Acknowledgment letters are a formal business communication used to acknowledge receipt of documents, services, or other items of value. Acknowledgment letters affirm that the document or item in question was received and serves as a legally binding record of its delivery. They provide an important form of evidence in any dispute that might arise concerning the transfer of goods or services. Written acknowledgement letters are concise and straightforward, but should be written in an engaging tone and style in order to create a positive impression on the reader.