eWall

Features

Works with any mail server
The SMTP service is the primary component of any mail server, and this is eWall's domain against the web threats and where it operates. That's why eWall works with any mail server.
Technologies
PHP + PostgreSQL + XML-RPC. This formula briefly outlines eWall's internals. As you can see, eWall is built upon reliable, time-proven technologies.
Fast multi-threaded service
eWall installs and runs as a high-performance Windows service.
Turnkey solution
eWall is ready to use out-of-the-box. The set of pre-defined filters start fighting SPAM and viruses immediately after installation. Only minimal, optional, configuration may be needed.
Zero maintenance
At pre-defined intervals, eWall deletes the old database records, quarantined emails and compresses the log files.
Self-updating
The installed components, such as ClamAV and Message Sniffer are pre-configured to automatically download and install any updates.
Quarantine
eWall has a Quarantine for filtered emails, which can be reviewed and appropriate messages forwarded on to the recipients.
Remote Control Panel
The eWall Remote Control Panel can be installed anywhere, and allows you to manage the eWall service itself, configure filters, and view the stats and logs in real time. Communications between eWall and the Remote Control Panel uses the XML-RPC channel, which transparent to regular firewalls. As a bonus, it includes a cool, animated dashboard, demonstrating the filtering process in pseudo-3D graphics.
Counterattack
eWall is also able to counter spammers with the tarpitting feature, wasting THEIR resources, with minimal resource consumption on your side.
Doesn't depend on .NET
... or any other framework. All necessary libraries are included in the installer.
WHOIS age, DNSBL, SURBL, SPF, DKIM, Greylisting, Anti-phishing, Greeting delay,
Harvester detection, Country blocking, Regular Expression (RegExp) searches
and many other anti-spam techniques are available in eWall by default. If that's not enough, eWall's open API architecture allows you to develop and add new filters quickly.
Message Sniffer
eWall supports the popular Message Sniffer engine — very fast and accurate commercial content scanner, developed by ARM Research Labs. The Message Sniffer has a high-performance multi-threaded core, which makes it suitable even for large ISP's.
Spam Assassin
Support for most popular, open-sourced spam filter, Spam Assassin is also included (SpamD).
AVG 2011, Avast 5, F-PROT 6, Sophos Antivirus 9.5
The support for these popular antiviruses is already included in Repository, and virtually any other command-line antivirus can be plugged in. Just request.
ClamAV
As an option, eWall can install the popular, open source antivirus, ClamAV.
Attachment filtering
By default, eWall enables the filters, stripping out the potentially dangerous attachments, even in packed archives.
Command-line scanners
Virtually any command-line antivirus scanner can be used with eWall.
SSL support
SSL listeners can be created to establish encrypted communications between eWall and mail sender.
Truly transparent
Unlike other mail proxies on the market, eWall can be truly transparent. Using the unique program EWLSP, included with eWall, the sender IP is not overwritten by eWall and is still available for use directly by the mail server, making all IP-based features on the email server available! (read more).
Open API
All eWall filters are open-source PHP scripts, that can be modified using the internal code editor or, for example, an external editor such as Notepad. This allows you to quickly develop complex and flexible filters, and share them with other eWall users.
Filters Repository
The pre-defined filters are stored in their own Repository, that represent a distributable XML file, open for editing and new filters.