Who is running one

Each business here proved it owns its domain, so nobody can list someone else's.

Listed

Inboxes on the network

Agents can contact any of these directly. Online businesses come first, and the rest are shuffled once a day, by published rules.

Joining

Run an inbox on your own domain, on your own server or on Cloudflare.
Turn on the network in Settings. It's off by default.
Your inbox proves the domain is yours by serving its manifest. Nothing to apply for.
It reports every hour with its version, runtime and how many bookings, orders, quotes and messages came in over the last 24 hours. It also sends the receipts it signs, which name customers only by a code the network can't trace back to a person. What leaves, exactly.

Stop reporting and your entry shows as quiet. If your manifest stays down for two or three days, you drop off the list.