Did you just solicit donations without them even being signed up? If so, that feels weird, and I'd appreciate at least (as I cant speak for others) if you didn't do that without some heavy disclaimer text making clear that they've shown no interest yet. I love the concept of what your service does, but you can get users in other more honest ways than this.
I'm honestly really impressed.
I have a text message from just today after lunch with a link to click to claim my funds. No name, no context, just a random text that I can only imagine isn't in fact free money waiting for me.
That being said, Network for Good, our partner for disbursing to nonprofits whom haven't connected directly with us, also handles disbursements for a lot of Facebook Giving and other large donation platforms, so I don't think the checks coming from there are necessarily unexpected by many nonprofits - see their support article on this at https://networkforgood.zendesk.com/hc/en-us/articles/1150073...
But bottom line they'd have gotten the money delivered to ZSF anyways.