Suzy-Q cable is used to low-level interact with newer chromebooks firmware, you can for example disable firmware write protection (previously it was done with a screw), debug hardware and unbrick chromebook

you can read on it a bit more in official Google docs: https://chromium.googlesource.com/chromiumos/third_party/hdctools/+/HEAD/docs/ccd.md

At my instance I did setup a email wildcard (receive emails from any address on that domain which don’t already have a account) and I get a lot of phishing and scam emails, most of them are send “to” /c/meta@femboys.bar, as link to this community is linked in sidebar, but I also seen emails “send to” random usernames

So yeah, It is happening, i wonder how bad it is on larger instances