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Stalwart

COMMS
Velocity6.3

Open-source all-in-one mail and collaboration server supporting SMTP, IMAP, and JMAP.

stalw.art ↗

Stalwart adds full SCIM v2 provisioning and 24-language calendar support as its standards coverage extends further than most commercial mail servers.

email-serverscimjmapenterprise-provisioningself-hosted
◆Current state
Stalwart is maintaining a weekly-or-faster release cadence, with alternating feature releases and dense bug-fix releases. The v0.16.20 release landed full SCIM v2 (Enterprise) including cursor-based pagination and the IPSIE lifecycle profile, conference links in calendar invites, and 24 new calendar interface translations. Below the feature line, the project is steadily closing correctness gaps across JMAP, CalDAV, IMAP, and MTA — many of them edge-case RFC compliance issues.
◆Where it's heading
Stalwart is building toward parity with commercial enterprise mail servers on identity federation and provisioning (SCIM v2, VAPID for web push, DMARCbis/DKIM2 already landed). The pace of RFC implementation is unusually aggressive for an open-source project; the combination of JMAP, CalDAV, IMAP UIDONLY/UIDBATCHES, and SCIM v2 positions it as a viable self-hosted alternative for organizations that need standards compliance without vendor lock-in.
◆Prediction
WebAuthn/passkey-based authentication and improved multi-tenant administration tooling are the most likely next capability additions, given the current trajectory toward enterprise identity management.

◆Recent moves

  1. 9d ago

    v0.16.21

    v0.16.21 fixes a batch of CalDAV, JMAP, IMAP, and MTA correctness issues — including IMAP pipelined command response ordering, WebDAV quota reporting for accounts without storage limits, and an LDAP authentication hardening against Active Directory's non-standard empty-password bind behavior.

    View source ↗
  2. 16d ago

    v0.16.20

    ⚡ SPARK

    v0.16.20 added full SCIM v2 provisioning (RFC 7643/7644 + cursor pagination + IPSIE lifecycle profile) as an Enterprise feature, conference links in calendar invites, and translations for 24 languages in the calendar interface — transforming Stalwart's enterprise identity integration story.

    View source ↗
  3. 22d ago

    v0.16.19

    v0.16.19 is a substantial correctness release addressing edge cases across CalDAV scheduling, JMAP (especially Calendar and Email/get), Meilisearch search, and MTA delivery — the kind of thorough compliance work that moves Stalwart closer to interoperability with finicky calendar clients.

    View source ↗
  4. 29d ago

    v0.16.18

    v0.16.18 switched GeoIP data sources to ip-location-db, added a RocksDB cache size cap, tuned RocksDB column families per access pattern, and fixed queue scheduler coalescing — infrastructure improvements that matter for high-volume deployments.

    View source ↗
  5. 1mo ago

    v0.16.17

    v0.16.17 added three IMAP extensions (UIDBATCHES, UIDONLY, MESSAGELIMIT/SAVELIMIT per RFC 9738), WebDAV Range header support, and switched to the maintained tikv-jemallocator — standards additions that improve compatibility with demanding IMAP clients.

    View source ↗
  6. 1mo ago

    v0.16.16

    v0.16.16 added JMAP Email Delivery Push Notifications (draft-ietf-jmap-emailpush-03) and system Sieve scripts can now access ORCPT during DATA — another JMAP standards implementation continuing the project's aggressive RFC coverage.

    View source ↗