15 Top Open Source Email Servers for Unix in 2025
The 15 top free and open-source email servers for Unix with setup guides, tutorials, videos, and instructions.
Email Server Screenshots
Forward Email
- IMAP
- SMTP
- MX
- SQLite Encrypted
Forward Email is an open-source email server for Unix. The official description from its website says, "Privacy-focused encrypted email for you. We are the go-to email service for hundreds of thousands of creators, developers, and businesses. Send and receive email as you@yourdomain.com with your custom domain or use one of ours."
Docker Mailserver
- IMAP
- SMTP
- MX
- SQLite Encrypted
Docker Mailserver is an open-source email server for Unix. The official description from its website says, "docker-mailserver, or DMS for short, is a production-ready fullstack but simple mail server (SMTP, IMAP, LDAP, Antispam, Antivirus, etc.)."
Maddy Mail Server
- IMAP
- SMTP
- MX
- SQLite Encrypted
Maddy Mail Server is an open-source email server for Unix. The official description from its website says, "Maddy Mail Server implements all functionality required to run a e-mail server."
Mail-in-a-Box
- IMAP
- SMTP
- MX
- SQLite Encrypted
Mail-in-a-Box is an open-source email server for Unix. The official description from its website says, "Take back control of your email with this easy-to-deploy mail server in a box."
mailcow
- IMAP
- SMTP
- MX
- SQLite Encrypted
mailcow is an open-source email server for Unix. The official description from its website says, "mailcow: dockerized is an open source groupware/email suite based on docker."
Dovecot
- IMAP
- SMTP
- MX
- SQLite Encrypted
Dovecot is an open-source email server for Unix. The official description from its website says, "Dovecot is an excellent choice for both small and large installations."
WildDuck
- IMAP
- SMTP
- MX
- SQLite Encrypted
WildDuck is an open-source email server for Unix. The official description from its website says, "WildDuck is a modern mail server software for IMAP and POP3."
Exim
- IMAP
- SMTP
- MX
- SQLite Encrypted
Exim is an open-source email server for Unix. The official description from its website says, "Exim is a message transfer agent (MTA) originally developed at the University of Cambridge for use on Unix systems connected to the Internet."
Postfix
- IMAP
- SMTP
- MX
- SQLite Encrypted
Postfix is an open-source email server for Unix. The official description from its website says, "It is Wietse Venema's mail server that started life at IBM research as an alternative to the widely-used Sendmail program."
chasquid
- IMAP
- SMTP
- MX
- SQLite Encrypted
chasquid is an open-source email server for Unix. The official description from its website says, "chasquid is an SMTP (email) server with a focus on simplicity, security, and ease of operation."
Haraka
- IMAP
- SMTP
- MX
- SQLite Encrypted
Haraka is an open-source email server for Unix. The official description from its website says, "A modern, high performance, flexible SMTP server."
Postal
- IMAP
- SMTP
- MX
- SQLite Encrypted
Postal is an open-source email server for Unix. The official description from its website says, "Postal is a complete and fully featured mail server for use by websites & web servers."
ZoneMTA
- IMAP
- SMTP
- MX
- SQLite Encrypted
ZoneMTA is an open-source email server for Unix. The official description from its website says, "ZoneMTA provides granular control over routing different messages. "
keila
- IMAP
- SMTP
- MX
- SQLite Encrypted
keila is an open-source email server for Unix. The official description from its website says, "Open Source Newsletter Tool."
listmonk
- IMAP
- SMTP
- MX
- SQLite Encrypted
listmonk is an open-source email server for Unix. The official description from its website says, "Self-hosted newsletter and mailing list manager."
Email Server Comparison
| Name | Description | Screenshot | IMAP | MX | SMTP | SQLite Encrypted | Website | Wikipedia |
|---|---|---|---|---|---|---|---|---|
| Forward Email ⭐ Suggested | Privacy-focused encrypted email for you. We are the go-to email service for hundreds of thousands of creators, developers, and businesses. Send and receive email as you@yourdomain.com with your custom domain or use one of ours. | Screenshot | Yes | Yes | Yes | Yes | Website | |
| Docker Mailserver | docker-mailserver, or DMS for short, is a production-ready fullstack but simple mail server (SMTP, IMAP, LDAP, Antispam, Antivirus, etc.). | Screenshot | Yes | Yes | Yes | No | Website | |
| Maddy Mail Server | Maddy Mail Server implements all functionality required to run a e-mail server. | Screenshot | Yes | Yes | Yes | No | Website | |
| Mail-in-a-Box | Take back control of your email with this easy-to-deploy mail server in a box. | Screenshot | Yes | Yes | Yes | No | Website | Wikipedia |
| mailcow | mailcow: dockerized is an open source groupware/email suite based on docker. | Screenshot | Yes | Yes | Yes | No | Website | |
| Dovecot | Dovecot is an excellent choice for both small and large installations. | Screenshot | Yes | No | No | No | Website | Wikipedia |
| WildDuck | WildDuck is a modern mail server software for IMAP and POP3. | Screenshot | Yes | No | No | No | Website | |
| Exim | Exim is a message transfer agent (MTA) originally developed at the University of Cambridge for use on Unix systems connected to the Internet. | Screenshot | No | Yes | Yes | No | Website | Wikipedia |
| Postfix | It is Wietse Venema's mail server that started life at IBM research as an alternative to the widely-used Sendmail program. | Screenshot | No | Yes | Yes | No | Website | Wikipedia |
| chasquid | chasquid is an SMTP (email) server with a focus on simplicity, security, and ease of operation. | Screenshot | No | Yes | Yes | No | Website | |
| Haraka | A modern, high performance, flexible SMTP server. | Screenshot | No | Yes | No | No | Website | Wikipedia |
| Postal | Postal is a complete and fully featured mail server for use by websites & web servers. | Screenshot | No | Yes | No | No | Website | |
| ZoneMTA | ZoneMTA provides granular control over routing different messages. | Screenshot | No | Yes | No | No | Website | |
| keila | Open Source Newsletter Tool. | Screenshot | No | Yes | No | No | Website | |
| listmonk | Self-hosted newsletter and mailing list manager. | Screenshot | No | Yes | No | No | Website |