Stalwart Keep: The Fastest Way to Run a Mail Cluster
A mail cluster spends its day asking small questions: is this message locked, has this client hit its limit, did anything change? Stalwart Keep is the server we built to answer them. It replaces Redis and a message broker with one service, finishes 99% of requests within 59 microseconds at a large deployment’s typical load, and has been through Jepsen.