Ask HN: Is there a list of charities that accept donations via PayPal?

I'm developing an android app which allows people to donate to charities via paypal, simple stuff. The hard stuff is getting email addresses of paypal accounts of charities that accept unsolicited donations. I tried mailing missionfish.org if i could send them money to their account but they answered with:

"We do not accept donations unless they are done via our programme. Our PayPal account does not accept unsolicited donations. If you'd like to donate to charities in our programme, you need to do so within our guidelines."

So if someone has experience with handling donations to charities on paypal i'd be thankful for response.