Scam Emails from admin@shegonna.mydns.jp

This is the 7th phishing email I got from admin@shegonna.mydna.jp already this morning! The scammer dumps phishing emails such as this, as well as revolting porn, day after day, often a dozen dangerous, and often dirty messages per day, like a plague of cockroaches. The scammers cannot be blocked; no mechanism bars him from my mailbox. The scammer is malicious, pernicious, and predatory. Why can't I keep him out, as I would a thief and a pervert from my door? I should have that right and that capability, but after months of attempting to block him, I cannot. PLEASE HELP STOP HIM.