This guide offers tips for writing acknowledgement letters to families for donations made in memory of a loved one. What do you need to include in your donation acknowledgment letter?This guide will cover everything from nonprofit memorial donation thank you letters to keeping track of memorial donations and how to notify families. A donation acknowledgment letter (sometimes called a donation receipt or thankyou letter) is an email or paper that recognizes a charitable contribution. 1. Personalize the message. Just like any well-written donor thank you letter, your memorial donation gratitude notes should be personalized to each donor.