Self-Hosted Email

License, age, maintenance and language

The table below covers every server listed on this page: whether it is open source, the year of its first public release, the latest release or commit we could verify on Nov 13, 2026, and the main language of the project. Facts come from official sites or project repositories, with a light link to the source. Where a fact is not published, that is stated rather than guessed. Several open-source suites are installers or Docker stacks around Postfix and Dovecot rather than new mail engines.

AI-written mail servers. We looked for email servers written by AI agents in C or Go. We did not find a production-ready, from-scratch C or Go mail server that its authors present as fully LLM-generated. MailPace published a write-up of vibe-coding an SMTP gateway in Rust (not C or Go) with Claude Sonnet 4, with the prompts in the git history of vibe-smtp; that project is experimental and is not recommended for production. Demir Mail Server is a GitHub Copilot-assisted installer and web UI around Postfix and Dovecot, not a new C or Go mail engine. Human-written Go mail servers already exist on this list (Mox and Maddy). Stalwart is written in Rust.

SMTP history and standards

SMTP was specified by Jonathan B. Postel in RFC 821, Simple Mail Transfer Protocol, in August 1982, replacing his earlier RFC 788 of November 1981. The same month, David H. Crocker's RFC 822 defined the format of ARPA Internet text messages. In November 1995, RFC 1869 added SMTP Service Extensions (ESMTP) and the EHLO command that later extensions use. The protocol and the message format were revised in RFC 2821 and RFC 2822 (April 2001), then again in RFC 5321 and RFC 5322 (October 2008). Those 2008 documents remain the current SMTP and Internet Message Format specifications (Draft Standard).

Later additions include a STARTTLS extension for running SMTP over TLS (RFC 3207, February 2002), a separate message-submission service (RFC 6409, November 2011, Internet Standard), and SMTPUTF8 for internationalized email (RFC 6531, February 2012). Clients typically collect mail with POP3 (RFC 1939) or IMAP (IMAP4rev1 in RFC 3501, replaced by IMAP4rev2 in RFC 9051); JMAP (RFC 8620 and RFC 8621) offers a newer JSON API. Domain authentication uses SPF (RFC 7208), DKIM (RFC 6376), and DMARC, which was first published as Informational RFC 7489 in March 2015 and was replaced in May 2026 by Proposed Standard RFC 9989 (from the DMARCbis work), together with RFC 9990 (aggregate reporting) and RFC 9991 (failure reporting). Related mechanisms include MTA-STS (RFC 8461), SMTP TLS Reporting (RFC 8460), DANE for SMTP (RFC 7672), and the experimental ARC protocol (RFC 8617). Citations were checked against the RFC Editor on Nov 13, 2026.

Text Only | Markdown	X	whois	history	safety	sitesearch	Google AI Mode	Grok	Bing AI
Open source
docker-mailserver.github.io - fullstack but simple mail server (SMTP, IMAP, LDAP, anti-spam, anti-virus) using Docker	X: none found	whois	history	safety	search		AI Mode	Grok	Bing AI
dovecot.org - open-source IMAP and POP3 email server (Community Edition)	X: none found	whois	history	safety	search		AI Mode	Grok	Bing AI
hmailserver.com - free, open-source email server for Microsoft Windows	X: none found	whois	history	safety	search		AI Mode	Grok	Bing AI
iredmail.org - free, open-source mail server solution for Linux and BSD	X: none found	whois	history	safety	search		AI Mode	Grok	Bing AI
maddy.email - composable all-in-one mail server	X: none found	whois	history	safety	search		AI Mode	Grok	Bing AI
mailcow.email - mailcow: dockerized, a mail server suite that runs in Docker	X: @mailcow_email	whois	history	safety	search		AI Mode	Grok	Bing AI
mailinabox.email - easy-to-deploy mail server in a box	X: none found	whois	history	safety	search		AI Mode	Grok	Bing AI
mailu.io - simple yet full-featured mail server as a set of Docker images	X: none found	whois	history	safety	search		AI Mode	Grok	Bing AI
modoboa.org - open-source email server with a web user interface	X: none found	whois	history	safety	search		AI Mode	Grok	Bing AI
postfix.org - Wietse Venema's mail transfer agent (SMTP server)	X: none found	whois	history	safety	search		AI Mode	Grok	Bing AI
stalw.art - open-source mail and collaboration server with JMAP, IMAP4, POP3, SMTP, CalDAV, CardDAV and WebDAV	X: @stalwartlabs	whois	history	safety	search		AI Mode	Grok	Bing AI
xmox.nl - Mox: modern, secure, all-in-one email server	X: none found	whois	history	safety	search		AI Mode	Grok	Bing AI
Commercial / proprietary on-premises
axigen.com - mail server software for on-prem and cloud-native deployment	X: @axigen	whois	history	safety	search		AI Mode	Grok	Bing AI
communigate.com - CommuniGate Pro unified communications server	X: @CommuniGate	whois	history	safety	search		AI Mode	Grok	Bing AI
gfi.ai - GFI KerioConnect: mail server with email, calendars, contacts and instant messaging for Windows, macOS and Linux, on-premises or hosted	X: none found	whois	history	safety	search		AI Mode	Grok	Bing AI
icewarp.com - business email and collaboration suite; cloud, on-prem or hybrid	X: none found	whois	history	safety	search		AI Mode	Grok	Bing AI
mailenable.com - Windows mail server software with webmail, CalDAV, CardDAV, antivirus and spam filtering	X: none found	whois	history	safety	search		AI Mode	Grok	Bing AI
mdaemon.com - MDaemon Email Server for Windows; a Microsoft Exchange alternative, on-premises or hosted	X: @MDaemon_Email	whois	history	safety	search		AI Mode	Grok	Bing AI
microsoft.com - Exchange Server Subscription Edition (SE), the current on-premises Exchange Server	X: none found	whois	history	safety	search		AI Mode	Grok	Bing AI
smartertools.com - SmarterMail, a business email and collaboration server for Windows and Linux	X: @SmarterTools	whois	history	safety	search		AI Mode	Grok	Bing AI
zimbra.com - email and collaboration software; Daffodil (v10) Professional and Standard editions require a license	X: none found	whois	history	safety	search		AI Mode	Grok	Bing AI