A Rust client for [Smol Mail](https://code.randogoth.com/randogoth/smolmail): a minimalist, end-to-end encrypted mail protocol over a Noise-secured TCP connection. `fumi` derives an identity from one 32-byte master secret, seals and opens mail, and talks to a mailbox; it is the counterpart to [bunshin](https://code.randogoth.com/randogoth/bunshin), the server.
Phase 1, the TCP carrier (SPEC.md 1.1), is implemented and interoperates in both directions with the reference client `smolmail.py` and the reference server `smolmaild.py`, and with `bunshin`. The Reticulum carrier of RNS.md (1.2) is not built yet: `smol+rns://` addresses parse and fail with a message naming the `rns` feature, and the flake does not yet vendor microReticulum.
Mail is stored sealed and opened on demand; there is no plaintext at rest. A first contact is learned by trust on first use and marked unverified when the server's key was not pinned; a key change is accepted only when a signed rotation chain leads from the key held to the one offered, and is surfaced rather than applied silently.
`bunshin` and the reference clients make a complete test rig: register against a local server, exchange mail in both directions, then rotate and fetch the mail that the superseded key still receives.
