Reply To: when someone says I should not reply

So… you blocked his number and he decided to respect your block?
No, he went around that and emailed you because he knows you don’t know how to block emails.
He is not respecting your boundaries. He is not respecting your request for him to leave you alone (request made by blocking his phone number).
Best to just not engage with him. He gave you the perfect out when he said he did not want to you reply. Even if he did not mean it, take him at his word on that. Respect his boundaries (when he says not to respond) when he did not respect yours (with the block).