Ask HN: How does tax deductibility work?

I'm building a site in which 501(c)(3) nonprofits can accept donations and fundraise through my service.

I understand that from the perspective of the user/donator, you should get an email telling you how much to claim on your 1040 Schedule A form. However, I'm clueless as to how to handle this from the perspective of my service. Do I simply report the actual amount transferred to the nonprofit after fees, or are there extra steps/forms to fill out that I'm missing?

(and since extra info can't possibly hurt: we're using Stripe as our payment processor)