Stalwart Mail Server
Stalwart Mail Server: A capable self-hosted mail stack with collaboration services, clustering and a free Community edition. Ranked #23 of 34 in Mail Server Software by our editors (6.9/10); pricing: Free plan · 30-day trial; best for modern, low-cost open-source mail hosting.
At a glance
- Editor score6.9 / 10
- PricingFree plan · 30-day trial
- Best forModern, low-cost open-source mail hosting
- Free planYes
- Paid from$1.09/user/yr
- License modelOpen-source
- Facts checked21 Sep 2026
Where it wins
- Free AGPL-3.0 Community edition for self-hosted deployments
- JMAP, IMAP, POP3, SMTP and built-in filtering
- CalDAV, CardDAV, WebDAV, clustering and distributed queues
Where it doesn't
- Self-hosted deployment requires your own infrastructure
- Web interface focuses on administration and account management
- Enterprise pricing varies by mailbox range and annual billing
Our verdict on Stalwart Mail Server
Stalwart Mail Server is a self-hosted mail and collaboration platform from Stalwart Labs for organizations running their own infrastructure. It combines JMAP, IMAP4rev1, IMAP4rev2, POP3 and SMTP services with calendars, contacts and file storage through CalDAV, CardDAV and WebDAV. Web-based administration, automated DNS, DKIM and TLS management, built-in spam and phishing filtering, clustering, high availability, fault tolerance and distributed SMTP queues make it suited to teams that want control over their mail environment rather than a hosted mailbox service.
Pricing is structured around a free Community edition and annual Enterprise licenses. Community costs $0 per server and is AGPL-3.0 licensed, with self-hosted deployment and standard mail and collaboration protocols. Enterprise starts at $2.40 per mailbox per year for 25–499 mailboxes, then costs $2.04 for 500–999, $1.74 for 1,000–4,999, $1.48 for 5,000–10,000, $1.25 for 10,000–49,999, and $1.09 for 50,000–99,999. Enterprise plans include unlimited domains, tenants, mailing lists and aliases, enterprise features, and licenses installable on unlimited servers. A 30-day free trial is also available.
Its ecosystem fit is practical for open-source infrastructure teams: supported clients and services include Apple Calendar, Apple Contacts, Mozilla Thunderbird, GNOME Evolution, KDE Kontact, and iOS and Android CalDAV/CardDAV clients. AI integrations include OpenAI, Anthropic and OpenAI-compatible self-hosted LLM endpoints. The main boundary is the user-facing mail experience: the current web interface is administration and account-management focused, while a dedicated built-in webmail client was planned but not an immediate priority. Choose Stalwart for self-hosted control, protocol coverage and collaboration services; choose another product if a built-in webmail client is central to the deployment.
Your product? Our editors can test Stalwart Mail Server in depth and publish a review, labelled as paid · from $99/mo →
Stalwart Mail Server pricing
All 8 Stalwart Mail Server plans and prices →
Stalwart Mail Server fact sheet
| Free plan | Yes |
|---|---|
| Paid from | $1.09/user/yr |
| License model | Open-source |
| Webmail interface | No |
| IMAP/POP3 access | Yes |
| Mobile sync | Yes |
| Antispam tools | Yes |
| Mailbox limit | 25 mailboxes |
| High availability | Yes |
| Free trial | 30 days |
| Deployment | Self-hosted, Browser extension |
| Platforms | Web, Linux |
| Support | Community, Docs |
| Built for | Small business, Mid-market, Enterprise (editorial estimate) |
| Integrations | 10 integrations: Apple Calendar, Apple Contacts, Mozilla Thunderbird, GNOME Evolution, KDE Kontact, iOS CalDAV/CardDAV clients … See all → |
| Pricing | Free plan · 30-day trial (source) |
| Website | stalwart.email |
| Facts checked | 21 Sep 2026 |
Stalwart Mail Server integrations
Stalwart Mail Server lists 10 integrations on its own site.
- Apple Calendar
- Apple Contacts
- Mozilla Thunderbird
- GNOME Evolution
- KDE Kontact
- iOS CalDAV/CardDAV clients
- Android CalDAV/CardDAV clients
- OpenAI
- Anthropic
- OpenAI-compatible self-hosted LLM endpoints
See all Stalwart Mail Server integrations →
Alternatives to Stalwart Mail Server
- Microsoft Exchange OnlineA Microsoft-centric hosted mailbox service with Outlook, archiving, compliance, and migration tools.9.3
- Zimbra CollaborationA broad open-source suite for organizations that need email, collaboration, and deployment control.9.1
- IceWarpA broad hosted email suite with collaboration, migration tools, and self-hosted deployment.9.0
See all Stalwart Mail Server alternatives →
Also Ranked In
Stalwart Mail Server is ranked in 2 of our directories.
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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
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