What do you need to include in your donation acknowledgment letter? Do your thank-you letters for donations truly convey gratitude?A donation acknowledgment letter (sometimes called a donation receipt or thankyou letter) is an email or paper that recognizes a charitable contribution. A donation acknowledgment letter is a type of donor letter that you send to donors to document their charitable gifts and donations. If you've donated to NJLERC, below please find a Donation Receipt form and a Donation Letter form that you can download and fill out. What to include in donor acknowledgment letters?