I advise 402 Payment Required \n Location: mailto:payment-offers@yourdomain. It’s still 4xx so they’ll probably know not to hit it repeatedly, and if they reach

I advise 402 Payment Required \n Location: mailto:payment-offers@yourdomain. It’s still 4xx so they’ll probably know not to hit it repeatedly, and if they reach out to negotiate payment, you have a choice whether to accept or not.