Courier
The Courier mail transfer agent (MTA) is an integrated mail/groupware server based on open commodity protocols, such as ESMTP, IMAP, POP3, LDAP, SSL, and HTTP. Courier provides ESMTP, IMAP, POP3, webmail, and mailing list services within a single, consistent, framework. Individual components can be enabled or disabled at will. The Courier mail server now implements basic web-based calendaring and scheduling services integrated in the webmail module. Advanced groupware calendaring services will follow soon.
The Courier mail server's source code should compile on most POSIX-based operating systems based on Linux, and BSD-derived kernels. The Courier mail server should also compile on Solaris and AIX, with some help from Sun's or IBM's freeware add-on tools for their respective operating systems.
The Courier mail server evolved out of several related projects, that merged together (more on that later). The Courier mail server implements SMTP extensions for mailing list management.
Learn more
hMailServer
hMailServer is a free, open source, e-mail server for Microsoft Windows. It's used by Internet service providers, companies, governments, schools and enthusiasts in all parts of the world.
It supports the common e-mail protocols (IMAP, SMTP and POP3) and can easily be integrated with many existing web mail systems. It has flexible score-based spam protection and can attach to your virus scanner to scan all incoming and outgoing email.
Learn more
Mailu
Mailu is a simple yet full-featured mail server as a set of Docker images. It is free software (both as in free beer & as in free speech), open to suggestions and external contributions. The project aims at providing people with an easily setup, easily maintained and full-featured mail server while not shipping proprietary software nor unrelated features often found in popular groupware.
Main features include:
Standard email server, IMAP and IMAP+, SMTP and Submission with autoconfiguration profiles for clients
Advanced email features, aliases, domain aliases, custom routing
Web access, multiple Webmails and administration interface
User features, aliases, auto-reply, auto-forward, fetched accounts
Admin features, global admins, announcements, per-domain delegation, quotas
Security, enforced TLS, DANE, MTA-STS, Letsencrypt!, outgoing DKIM, anti-virus scanner, Snuffleupagus, block malicious attachments
Antispam, auto-learn, greylisting, DMARC& SPF, anti-spoofing
Learn more
FreeIPA
Manage Linux users and client hosts in your realm from one central location with CLI, Web UI or RPC access. Enable Single Sign On authentication for all your systems, services and applications. Define Kerberos authentication and authorization policies for your identities. Control services like DNS, SUDO, SELinux or autofs. Integrated security information management solution combining Linux (Fedora), 389 Directory Server, MIT Kerberos, NTP, DNS, Dogtag certificate system, SSSD and others. Built on top of well-known Open Source components and standard protocols. FreeIPA is an integrated security information management solution combining Linux (Fedora), 389 Directory Server, MIT Kerberos, NTP, DNS, Dogtag (Certificate System). It consists of a web interface and command-line administration tools.
Learn more
