Not necessarily.
Incoming email: port 25 is blocked on many residential connections.
Outgoing email: If you send email from a residential IP block you're likely going to be flagged as spam.
Elsewhere in the thread, Giri says it uses a VPN connection. Is it TLS + something else?
helm.garrytan.com:3333 for example responds with a self-signed localhost cert, not LE keys. IMAPS (still not sure why that’s there but I asked that in a different comment so let's have that thread there) and 8443 do answer with LE though :)