While almost all charities rely on a set of donor appreciation strategies, their effectiveness for the success of fundraising campaigns is underresearched. Through two preregistered field studies conducted in collaboration with a leading German opera house (N = 10,000), we explore the significance of expressing gratitude and examine two different approaches to doing so. Our first study investigates the impact of a ‘thank you in advance’ statement in fundraising letters, a common strategy among fundraisers. In the second study, we explore the effectiveness of handwritten thankyou postcards versus printed postcards, shedding light on the roles of personalization and handwriting in donor appeals. Our findings challenge conventional wisdom, revealing that neither ‘thank you in advance’ nor handwritten thank you notes significantly affect donor contributions.
