Anti-spam email/messaging protocol that is simple, cheap to implement, directly compatible with email/messengers, low false negative rate compared to current spam filtering, free for senders, and does not require the sender to pay to send a message. For people who receive too much marketing spam, survey spam, low-effort cold emails, and want to be able to easily filter spam successfully because you do not want to waste time on them.

Future-proofed and will work on AI spam in the future too, unlike current spam filtering methods.