OpenSource Mail Server

I have just completed another mail server install using Postfix, Dovecot and Roundcube.
Dovecot is an open source IMAP and POP3 email server for Linux/UNIX-like systems, written with security primarily in mind. Dovecot is an excellent choice for both small and large installations. It’s fast, simple to set up, requires no special administration and it uses very little memory.
Some of the most notable features of Dovecot include:

Dovecot is among the highest performing IMAP servers while still supporting the standard mbox and Maildir formats. The mailboxes are transparently indexed, which gives Dovecot its good performance while still providing full compatibility with existing mailbox handling tools.
Dovecot is standards compliant. Dovecot v1.1 passes all IMAP server standard compliancy tests while most other servers fail many of them.
Dovecot’s indexes are self-optimizing. They contain exactly what the user’s client commonly needs, no more and no less.
Dovecot is self-healing. It tries to fix most of the problems it notices by itself, such as broken index files. The problems are however logged so the administrator can later try to figure out what caused them.
Dovecot tries to be admin-friendly. Common error messages are made as easily understandable as possible. Any crash, no matter how it happened, is considered a bug that will be fixed.
Dovecot allows mailboxes and their indexes to be modified by multiple computers at the same time, while still performing well. This means that Dovecot works well with clustered filesystems. NFS has caching problems, but you can work around them with director proxies.
Dovecot’s user authentication is extremely flexible and feature-rich, supporting many different authentication databases and mechanisms.
Postfix 2.3+ and Exim 4.64+ users can do SMTP authentication directly against Dovecot’s authentication backend without having to configure it separately.
Dovecot supports easy migration from many existing IMAP and POP3 servers, allowing the change to be transparent to existing users.
Dovecot supports workarounds for several bugs in IMAP and POP3 clients. Since the workarounds may cause the protocol exchange to be slightly less optimal, you can enable only the workarounds you need.
Dovecot’s design and implementation is highly focused on security. Rather than taking the traditional road of just fixing vulnerabilities whenever someone happens to report them, I offer 1000 EUR of my own money to the first person to find a security hole from Dovecot.
Dovecot is easily extensible. Plugins can add new commands, modify existing behavior, add their own data into index files or even add support for new mailbox formats. For example quota and ACL support are completely implemented as plugins.

Click here for details on Postfix

About the Roundcube webmail project

This project is a free and open source webmail solution with a desktop-like user interface which is easy to install/configure and that runs on a standard LAMPP server. The skins use the latest web standards such as XHTML and CSS 2. Roundcube includes other sophisticated open-source libraries such as PEAR, an IMAP library derived from IlohaMail the TinyMCE rich text editor, Googiespell library for spell checking or the WasHTML sanitizer by Frederic Motte.

Released features

Available in over 70 languages
Drag-&-drop message management
Full support for MIME and HTML messages
Sophisticated privacy protection
Compose messages with attachments
Multiple sender identities
Full featured address book with groups and LDAP connectors
Find-as-you-type address book integration
Richtext/HTML message composing
Forwarding messages with attachments
Searching messages and contacts
Threaded message listing
IDNA support
Spell checking
IMAP folder management
Shared/global IMAP folders
Support for external SMTP server
Support for access control lists (ACL)
Built-in caching for fast mailbox access
Unlimited users and messages
Template system for custom skins
Plug-in API for flexible exensions

Planned features

Support for PGP and S/MIME encryption
Online calendar module
Saved mail and address book searches
Keyboard shortcuts
Attachment previews
Import/export functions
Admin interface

See the development roadmap for more.

Server Requirements

Apache, Lighttpd, Cherokee or Hiawatha web server
PHP Version 5.2.1 or greater
MySQL, PostgreSQL, SQLite or MSSQL database
An IMAP server which supports IMAP4 rev1
An SMTP server (recommended) or PHP configured for mail delivery