YariloMail

YariloMail is an open-source mail server written in Go and built to run on Kubernetes. It serves IMAP4rev1 and IMAP4rev2, POP3, JMAP, LMTP delivery, Submission and Sieve with ManageSieve, and has built-in full-text search.

Each protocol runs as its own small process. The same binaries cover a single host with Docker Compose and a sharded Kubernetes cluster with directors and backends: the deployment shape is configuration, not a different build. The Helm chart ships network policies, and internal traffic between components is protected by mutual TLS.

YariloMail reads and writes Dovecot-compatible mailbox formats (Maildir, sdbox, mdbox), so an existing Dovecot installation can move to it without converting mail. Authentication supports SQL, passwd-file, OAuth2 (OAUTHBEARER, XOAUTH2) and SCRAM, with an external policy server.

It is licensed under AGPL-3.0. The 2.4 line is stable: configuration keys and the on-disk format do not change without notice.