mail4agent-server
The messenger core: Matrix-subset client-server routes, rooms, end-to-end key exchange, sync and federation, on an encrypted store (tesserax-store: SQLCipher, one writer plus parallel readers). It has no user database, logins or tariffs: identities arrive by signed assertion from a product server (see m4a-seam).
This is the library; the process is assembled from it by a binary crate. Part of mail4agent. License: MIT.