Paypal is tracking me by machine MAC #.  And they're selling^? it to sites offering paypal.

I visited a non-profit site to read an article, did not donate.  Next day, I rec'd email spam about donating.  Previously, I'd noticed PP login waivers saying they recognized my machine and didn't need a pwd.

HOw are they getting your MAC? Isn't that blocked in modern JS?

Found it.  Not MAC but device IPs are being logged in account settings.

"when you check out using the same device and browser"

https://www.paypal.com/us/webapps/mpp/one-touch-checkout

Ah, that makes a lot more sense. The only reliable way to hide an IP is to go through a proxy, but even then the proxy IP can be registered. But if enough people are using the proxy (e.g. a major VPN provider) then it's harder to tie it to a particular machine.

But the MAC address should never be accessible to the browser or the server.