What is this?
The payjoin mailroom is a lightweight binary that bundles the two server-side roles required by BIP 77 Async Payjoin: a directory and an OHTTP relay. Together, they let sender and receiver complete a payjoin without being online at the same time, while keeping network identities private.
Payjoin Directory
A store-and-forward mailbox that holds small, ephemeral, end-to-end encrypted payloads for asynchronous payjoin.
OHTTP Relay
An Oblivious HTTP proxy that separates client IP addresses from the directory, preventing it from correlating users with their network identity.
OHTTP privacy requires that these two roles be operated by different parties. The mailroom enforces self-loop detection: requests where the relay and directory resolve to the same mailroom are rejected. Wallets should always pick distinct mailrooms for their relay and directory.