I agree. I hand-addressed all the envelopes. Even though the letter itself was always a form letter, I wrote something personable on each letter such as "thanks for anything you can do" or something like that. I think I'll try your approach and see what I can get. Thanks!
What I did was email to find the name and address of the person responsible for donations. Then I went and wrote a small note when I sent our donation request letter that's on our school's letterhead. I seem to have alot of success that way. I also handwrote the envelopes, not using computer generated labels. I felt that this was more of a warm touch. Not sure if that made much of a difference, but I think I've been pretty successful so far.
Have you had more success in your organization's activities by finding an e-mail address and sending it to a person at that company or writing a letter to the attention of Customer/Community Relations?