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Compare editions

Discover the differences between the open source and enterprise editions.

Features comparison

Compare the comprehensive features of our open source and enterprise editions.

Features marked with yellow checkmarks are currently under development. For scheduled release dates, please check our GitHub page.

If you have questions please read the licensing FAQ.

Open-source
Free
Enterprise
Pricing upon request
Message Store
JMAP Core
JMAP Mail
JMAP for WebSockets
JMAP Blob
JMAP for Quotas
IMAP4rev1
IMAP4rev2
POP3
Full-text search
Autoconfig
Disk quotas
Sub-addressing & Catch-all
Mailing lists & Aliases
MTA
Programmable
Rate & concurrency limiting
Distributed & fault-tolerant queues
Queue quotas
Milter integration
Unlimited virtual queues
Delayed & priority delivery
Envelope rewriting
DKIM
SPF
ARC
DMARC
DANE
MTA-STS
TLS Reporting
Report analysis
Scripting & customization
Sieve Support
ManageSieve
JMAP for Sieve Scripts
REST API
Webhooks
Spam & fishing filtering
Spam rules
Statistical classifier
DNSBL
Collaborative filtering
Phishing protection
Trusted reply tracking
Sender reputation
Greylisting
Spam traps
AI classifier -
Contacts & Calendars
CardDAV
CalDAV
JMAP for Contacts
JMAP for Calendars
JMAP Tasks
ActiveSync
Backend support
RocksDB
FoundationDB
mySQL/MariaDB
SQLite
S3-compatible
Redis
ElasticSearch
OpenTelemetry
Prometheus -
Authentication
LDAP
SQL
OAuth
OIDC
WebAuthn & Two-factor authentication
App passwords
Third-party OIDC providers -
SAML -
Security & Encryption
Encryption-at-rest
ACME
Access Control Lists
Fail2ban
Rate limiting
Security Audited
Memory safe
Web-admin
Account management
Queue management
Report visualization
Configuration management
Self-service portal
Log viewer
Dashboard -
Metrics -
Alerts -
Cluster & HA
Distributed
Fault tolerant
Coordinator-less
Proxy protocol
Enteprise features
Multi-tenancy -
Branding -
AI-powered -
Lawful interception -
Support
Community support
Premium support -
Dedicated Support Engineer - On demand
Custom SLA - On demand
Learn More Learn More

LICENSING FAQ

If you don't see an answer to your question, you can send us an email from our contact form.

Stalwart Labs aims to provide a robust and feature-rich mail server solution. However, sustaining long-term development for such a project requires significant financial resources. Currently, we do not have enough open-source sponsors to cover these costs fully.

To bridge this funding gap and ensure the developers can work full-time and exclusively on enhancing Stalwart Mail Server, we offer a paid Enterprise version. The revenue from the Enterprise version is crucial for maintaining the quality and progress of both the paid and open-source versions.

Moreover, having a paid Enterprise version directly benefits the open-source community. The continuous development funded by the Enterprise version allows us to introduce new features and improvements to the open-source version as well.

It's important to note that the open-source version of Stalwart Mail Server already boasts more features than any other open-source or paid mail server solution available in the market. We are committed to maintaining and expanding this lead.

We invite you to become a sponsor if you wish to support the open-source development further and help us release more features as open source in the future. Your sponsorship can make a significant difference in the project's growth and sustainability. Thank you for your understanding and support.

Yes. At Stalwart Labs, we are committed to maintaining the integrity and accessibility of Stalwart Mail Server as an open-source project. We understand the concerns arising from past incidents where popular open-source projects have changed their licensing models or moved certain features behind a paywall. We want to assure our community that we have no intention of doing a "rug pull."

Stalwart Mail Server will remain under the AGPLv3 license, and we will not change any existing open-source features into paid ones. Our commitment to the open-source community is unwavering, and we promise to keep the current open-source version fully accessible and free.

Our paid Enterprise version exists solely to support the long-term sustainability and development of the project. It allows us to fund full-time development and ensure that Stalwart Mail Server continues to grow and improve. The open-source version will continue to receive updates, enhancements, and new features as part of our ongoing commitment.

We appreciate the trust and support of our users and contributors. If you have any questions or concerns, please feel free to reach out to us. Thank you for believing in Stalwart Mail Server and our mission to provide a powerful, open-source mail server solution.

Our Enterprise licensing for Stalwart Mail Server is designed to be flexible and scalable to meet the needs of various organizations. Licenses are sold on a per-mailbox basis, allowing you to purchase only what you need, and charges are applied monthly, providing a straightforward and predictable cost structure.

We offer a tiered pricing scheme, meaning the more mailboxes you license, the lower the cost per mailbox. For those who prefer an annual billing cycle, we provide attractive discounts as an incentive for yearly payments.

Once you purchase an Enterprise license, you will receive a license key. This key is used to activate the Enterprise features in Stalwart Mail Server, unlocking advanced functionality and premium support.

Our goal is to provide a flexible licensing model that grows with your organization and offers the best value for your investment. If you have any questions about our licensing options or need help selecting the right plan for your needs, our support team is here to assist you.

To upgrade to the Enterprise version of Stalwart Mail Server, please contact us using the form provided on our website or via email. Our team will respond promptly with a customized quote and payment details based on your specific needs and the number of mailboxes you wish to license.

We are actively working on making the upgrade process more automated. In the future, you will be able to manage your Enterprise subscription directly from Stalwart's web-based management interface, providing a seamless and convenient upgrade experience.

For now, our support team is here to assist you through the upgrade process and ensure you have all the information you need to make the transition to Enterprise. If you have any questions or need further assistance, please don't hesitate to reach out to us.