Ask HN: Is Gmail's unsubscribe feature safe?

Got a spam email today. It had an unsubscribe link pointing to a random Azure blob. I click "Mark as Spam" and it offers me to unsubscribe instead?

This was worring as I thought ... well the unsubscribe is a dangerous link so how will it do it.

Turns out it uses a header like X-Unsubscribe-Web. I checked what that was set to, and in this spam it was a well known online newspaper plus a bogus query string. So they probably put a plausible link (i.e. not a black list) to fool Google.

But in general X-Unsubscribe-Web could be set to something malicious, right?

And why is Google even discouraging me from reporting spam (or in this case... phishing).

Edit: I see there is now a report Phishing and that button treats me like an adult :-)