Ask HN: How does LinkedIn evade SPAM?

I continuously mark Linkedin emails as SPAM. They start getting caught in the SPAM box (Fastmail) but after a while, I start receiving them again in my inbox. I, then, proceed again to mark them as spam but it takes at least a couple dozen for them to be recognized as such.

I have two questions:

1. What is it that Linkedin does to keep resurfacing to my inbox?

2. How come Linkedin is not penalized for the atrociously enormous quantities of spam it sends? (either by mail processors or by the authorities). I have lost count of how many times I have turned notifications off.