I'd ask in response if you've ever seen an organization asking for volunteers that isn't also asking for money.

If you can volunteer in addition to sending money, depending on the org they will have some shitwork to do that is unpleasant/monotonous (would cost money to get someone to do) and low-skilled (you probably won't screw it up, and they don't have to waste skilled staff on it - and the skilled staff hate doing it even more than you will.)