Created by Martin Knafve, hMailServer is an open source, free email server for Windows. This server includes administration tools for backup and management. It supports SMTP, IMAP, and POP3 email protocols, as well as distribution lists, anti virus scanning, virtual domains, and much more

Features

The hMailServer uses database engines such as MySQL, PostgreSQL, or MS SQL (depending on your choice) to store index data and configuration. The actual email messages, however, are stored on disk in a raw MIME format. This email server comes with a nice COM library that you can easily use for integration. It also features development forums and active support.

The hMailServer also features account and domain signatures for advertising and legal footers, retrieval of messages from POP3 accounts, server side rules, attachment blocking, and quotas on mailbox, domain, and individual message sizes. It has custom SMTP routes for certain domains and plus (+) addressing. With API, you can write hMailServer scripts utilizing Jscript and VBScript.

Version 5 of the hMailServer has SSL support. In the existing version (Version 4), you must use external software like STunnel to achieve SSL support.

AntiSpam

The hMailServer offers several different AntiSpam mechanisms such as URL based DNS blacklisting (SURBL) and Host based DNS Blacklisting (DNSBL). Other mechanisms include built-in SpamAssassin integration in v5, SPF, and Greylisting (you must retry sending in order for the message to succeed).    

Advantages

One of the many advantages of hMailServer is that it is lightweight but very commanding email server software. The program is user friendly, fast, and stable. Learning its interface is easy and you will be familiar with it in no time.

The hMailServer also has the ability to utilize clamwin and spamhaus blacklist (both free to use) as its external antivirus. Clamwin itself is useless for regular use since it does not have real time scanner. Coupled with hMailServer, however, you can have a powerful combination. This makes Mdaemon email server seem pointless.

Additionally, the hMailServer provides log support and excellent backup service so you do not have to fret over the hassle of backing up the email server. It can compress anything, from your email accounts to the messages on the server. This saves you significant amount of time. Overall, the hMailServer is an interesting, excellent, and highly recommended software.