Open Source Anti-Spam Software Review – ESVA Email Security Virtual Appliance (ESVA)

Looking for a ‘Free (no cost) and easy’ anti-spam or spam blocker solution for your organization that supports multiple email domains?

Looking for an anti-spam solution that can be deployed to your production environment in less than 20 minutes?

ESVA Email Security Virtual Appliance (ESVA) is a free software-based anti-spam solution created by Andrew MacLachlan since 2005. ESVA is a pre-built virtual appliance that runs on virtual machines. The latest version of ESVA can be run on VMWare, running on Citrix XenServer, Microsoft Hyper-V and VMware platforms.

The development of the application was stopped for almost 2 long years until the day after the release of version 2058. I was very happy that the current version 2060 is not available. To download the latest version, visit the official ESVA GD website.

The main components of ESVA are:

• CentOS – Robust operating system cloned by Red Hat
• MailScanner – Anti-spam package for email gateway systems.
• MailWatch – web-based administration page for MailScanner
• Postfix – Email System
• SQLgrey – Gray List Filtering
• Webmin – Web Based Administration Page CentOS and Postfix Administrator
• ClamAV – Open Source Antivirus
• Distributed Checksum Clearinghouses (DCC) and Vipul’s Razor – Mass Spam Detection
• Pyzor – Detecting the spam network
• SpamAssassin – popular spam filtering package for header, text analysis, Bayesian filtering, DNS blocklists, and database filtering
• FuzzyOCR – filtering content and properties of images based on fuzzy logic
• MailGraph – Mail Statistics Graphing Tools

Why use ESVA?

The advantages of using ESVA are:

1. Cost free
2. robust,
3. filtering accuracy
4. sender domain and blacklist
5. sender domain and whitelist
6. quarantine and release report (per user or per domain)
7. Easy to use and personalized.

I have deployed self-customized version of ESVA in our data center since 2007 and it is still one of the best anti-spam solutions. Although, Bayesian filtering method requires time to build the database of SPAM or HAM. Over time, ESVA’s mail filtering becomes more effective at distinguishing between ham and spam compared to some commercial products.

We have 2 ESVA units deployed at layer 2 running our data center to take care of 500+ domains and 10,000 email volumes per hour. Our ESVA is used for email quarantine, virus scanning, fuzzy OCR, and Bayesian filtering.

However, some important features that I think the author should include:-

1. No SMTP authentication or LDAP integration
2. No filtering issues
3. No keyword filtering
4. Invalid GIF and JPEG filtering

Some of the weaknesses mentioned above can be solved by customizing scripts. However, I need to figure out the function of each package, complement and file path. I am currently compiling FAQs and customization settings and hope that anyone using ESVA can benefit from it.

However, ESVA is one of the most effective and powerful FOSS-based spam solutions I’ve ever implemented. It will definitely help your organization with spam problems.