I donate to a few charities, usually a chunk of money once or twice a year for each. They include the local domestic violence refuge, the Indigenous Literacy Fund (as an ex-English teacher and ex-librarian, that seems appropriate), the Fred Hollows Foundation (eye operations in poorer areas of the world), some charities for homeless people, and also for the last few decades I have donated monthly to Amnesty International.
Most of the messages I receive are via email, but I have been getting regular mail from one of the more recent charities I donated to and I'll be contacting them to ask them to stop wasting good money on paper, printing and postage.