An acknowledgement receipt email lets the sender know you have received their email and you are looking into it. What do you need to include in your donation acknowledgment letter?Here's an example of how to acknowledge receipt of these emails in a relaxed, but prompt manner. Clearly list the purpose of the receipt and include the name of the items or documents you're distributing and the date. The letter serves as a thank you and required written acknowledgment, and should include specific language from the downloadable template for tax purposes.