When you layer in the costs of junk mail to the environment, et cetera, it's a pretty clear thing, like, don't send stuff. A third bullet point would be that you can't expect everyone to donate to everything. Research by deborah small says people's personal preferences actually matter. So i think when you design these campaigns, you should think about targeting people who just personally care for maybe idiosyncratic reasons.
Is it O.K. to bother people for a good cause? Why do people donate to charity in the first place? And do those personalized address labels actually make people get out their checkbooks?