Stalwart is a self-hosted email and collaboration infrastructure that provides an integrated mail server supporting SMTP, IMAP, POP3, and JMAP protocols. It functions as a comprehensive communication hub, combining email hosting with a collaboration server for shared calendars, contacts, and files.
The system distinguishes itself through a distributed architecture that uses peer-to-peer cluster coordination to ensure high availability and fault tolerance. It features a built-in security suite that implements an S/MIME and OpenPGP email gateway alongside automated TLS certificate provisioning via the ACME protocol.
The platform covers a broad range of capabilities, including multi-layer sender authentication, scriptable mail routing through Sieve and regular expressions, and full-text content indexing. It also provides identity and access management through support for LDAP, SQL, OIDC, and OAuth, while offering administrative tools such as a web dashboard and automated DNS record management.
System health is monitored via Prometheus and OpenTelemetry, and the server supports pluggable storage backends including S3-compatible blob storage.
