A sample of things I have received from people by e-mail, by mistake -- sometimes by people I don't even know.<p>- Someone's complete passport in pdf.<p>- Someone's complete contact list, with names, addresses, e-mails, phone numbers, employers, age. I'm sure all these people would be thrilled to know.<p>- Someone's legal will, complete with lawyers' comments and bank account details.<p>And this is just a sample from e-mail mistakes.<p>Much is said of software vulnerabilities, malicious hacking, et al. But good grief, people can't even use e-mail yet in 2022.
Delete the documents and let the sender know they shouldn't send stuff like that by email.<p>As for "deal with," I don't know what kind of answer you expect. You can only do so much to protect people from themselves. How to deal with people who can't drive a car safely? Who can't do their job? Who can't organize a meeting to not waste everyone's time? Sometimes you avoid them, sometimes you try to help, sometimes you just have to endure and remind yourself you can't control or change everyone's behavior.
You need to deal with the root societal cause: computers are too easy to use. So start advocating for them to be harder again. People won't be sending you random documents if they can't configure their modem.