My reply (I didn't reply to his first spam):
> I don't know where you got my email address from but your first email was spam (unsolicited email).
At least one other SE user has confirmed that he received the same spam.
Please go way before I file an official complaint with your colleagues, your ISP and your hosting provider.
You might also care to read https://meta.stackexchange.com/questions/291029/unsolicited-email-from-a-startups-user-my-email-is-not-public and explain your behaviour to the Stack Exchange community.