Stalwart Mail Server is an open-source mail server solution with JMAP, IMAP4, and SMTP support and a wide range of modern features. It is written in Rust and designed to be secure, fast, robust and scalable. Key features: JMAP server: JMAP Core (RFC 8620) JMAP Mail (RFC 8621) JMAP for Sieve Scripts (DRAFT-SIEVE-19) JMAP over WebSocket (RFC 8887), JMAP Blob Management (RFC9404) and JMAP for Quotas