Protonmail's customer service agent CCed my recovery email (me) in the email thread where the attacker was social engineering them. And the attacker was successful until I had to reply to the email chain myself to tell them to stop.
And yes, signing up to Home Depot's email newsletter and other services so that they could tell the customer service agent "my last few emails were from Home Depot and ..." was successful against their customer support system. That's just how amazing it is.
Finally, I don't expect the social media guy running protonmail's HN account to give us much insight into protonmail's customer support security issues, but if you're going to show up, I would've at least expected you to forward my email somewhere for follow up.
