General Donation Form. In this post, I'm breaking down how to write a donation letter.Complete a copy of our donation form. Mail your check and donation form to: United Way of Central Maryland P.O. Box 64282. This is the simplest online donation form template that you can use without any code requirement and accept donations in the easiest way. Try our free donation request letter templates! Download our standard template or check out our example letters for events, auctions, schools, and more.