The PayPal Giving Fund seems good enough that I feel like there must be a catch, but looking at it I think it's fine. So either there's something I'm missing, or we should be sending basically all large donations via the fund.

The idea is, PayPal maintains a 501c3 that you donate to, then they batch the donations and send them on to the charity you chose, and PayPal covers all transaction costs. If you're funding PayPal with a credit card, then you still get the associated rewards (cash back etc). There is administrative overhead for the recipient charity, similar to as if you had sent a check, so it doesn't make sense to do this for small donations, but for large ones it looks like this is a way to donate $10k and then get $150 back from your credit card via PayPal.

Charities have to sign up for this, and I noticed that the AMF has, so I wrote to them to ask what they thought of it. Rob wrote back:

Yes, it's a good way of giving as the fees are zero and the admin for us is light. It is on a par with donating via check and bank transfer.

Currently the AMF recommends check or bank transfer for amounts over $5k, so it sounds like that's the threshold to apply here as well.

So: is there a reason not to use this?