Pick the edition that fits your deployment.

Sustaining full-time development of a mail and collaboration server requires funding that open-source sponsorship alone has not covered. To bridge that funding gap and keep developers working full-time on Stalwart, we offer a paid Enterprise edition. Revenue from Enterprise subscriptions directly benefits the open-source community: it pays the engineers who continue to maintain and extend the Community edition under AGPL-3.0, and it lets us release new features on the open-source side over time. The Community edition already includes more functionality than most paid alternatives, and we are committed to growing that lead. If you want to help move more features to AGPL, become a sponsor: your contribution makes a meaningful difference to the project's growth and sustainability.

Yes. We understand the concerns raised by past incidents where popular open-source projects changed their licensing model or moved existing features behind a paywall. We have no intention of doing a "rug pull". Stalwart will remain under AGPL-3.0, and we will not reclassify any existing open-source feature into a paid one. The Enterprise edition exists solely to fund the long-term sustainability of the project. The open-source version continues to receive updates, enhancements and new features as part of our ongoing commitment to the community.

The Enterprise license includes additional features and integrations designed for large-scale or complex deployments: multi-tenancy with per-domain directory backends, multi-tenant branding, account archiving and un-deletion, the AI / LLM spam classifier, AI-assisted Sieve scripting, read replicas, sharded blob and in-memory stores, live telemetry, message delivery history, dashboards and metric alerts. The full breakdown is in the table above and on the Enterprise edition page. To qualify for Premium Support, your organisation must subscribe to 150 or more mailboxes under the Enterprise license.

Enterprise licensing is sold per mailbox as a subscription, giving you a flexible and scalable model that fits any organisation. You only pay for what you need, billed annually or monthly, with a predictable cost structure. The pricing is tiered: the more mailboxes you license, the lower the per-mailbox cost. The full table is on the pricing page. After purchase you receive a license key that activates the Enterprise features. Keys are issued to a server domain name and can be used on an unlimited number of servers under that domain. For example, a license issued for *.example.org can be installed on mx1.example.org, mx2.example.org and any other server under example.org, with no additional licensing. Although the license is issued to a specific server domain, the deployment can still host an unlimited number of client domains: a license registered for *.example.org can serve mail for foobar.org, customer.com or any other domain your users send and receive mail under. The domain restriction applies only to the server hostnames, not to the domains the server provides email service for.

Upgrading is a fully automated process. Visit the Stalwart Labs Licensing Portal. Credit-card purchases are issued instantly, so your license key is available immediately and activates the Enterprise features as soon as it is installed on the server.

Yes. We offer a 30-day trial license with full access to every Enterprise feature, available at license.stalw.art/trial, so you can evaluate Enterprise in your own environment before committing.

If you cancel, the server reverts to the Community edition automatically. Enterprise-only features stop, but no data is lost and no service is interrupted: mailboxes, calendars, contacts, file storage and configuration remain intact, and standard email and collaboration service continues without disruption for your users.