Step 1/2: Create an offer
The Bitcoin SV wallet Money Button has a feature where any transaction can include somewhat arbitrary data. This site utilizes that feature by showing in a single transaction a paid ad, which looks like this:
🔴 Hey! I want to buy your paymail address firstname.lastname@example.org. How about 78.00 USD for it? If interested, please send email to: email@example.com. This offer is valid until 2023-04-02. Sent from Paymail.biz.
The offer will be sent as a 1 cent payment to the paymail owner's Money Button wallet. If you'd like to see first-hand how the message looks like, send an offer to any paymail address you already own.