Where can we collect and share photos online without having to sign up?

Gabriel’s organisation works with community groups on volunteering, and they want to collect photos of all the various projects as simply as possibleOnce a year we hold a big day of international volunteering. Community groups, churches, synagogues and so on organise their own projects under our banner. We encourage them to take photos of their project and send them to us.We would like to find a system that lets them upload photos easily, to a secure folder, without having to sign up for a