The Linux foundation is in the same league: They are sending me spam^Hmarketing communication, but when I want to unsubscribe they tell me that I have an invalid email. The provider of that address ended up on some self-declared blacklist years ago for some time, which might explain part of it. But not stopping to sending email to those you don't want to deal with is nonsense. Not accepting unsubscribes probably illegal in many countries.
