[usr1106]

To elaborate on that, my local library has a pretty dumb laser printer. I don't think it has the memory to store many pages and no significant internet-facing functionality (apart from accepting files if they configued it badly). So I don't think there are significant risks sending my documents thorugh it.

But the city main library has some smart "document center" machine. Amongst other it can "print to pdf" for the paperless age. In other words scan. And send the results to an email address you enter on the touchscreen. Here I would be pretty worried what insecure operating system and software that machine is running. I wouldn't be suprised to read a headline on hackernews that the last 1000 pages printed/scanned on such type of machine are all publicly accessible on the internet...