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

Looking for a ‘Free (No Cost) and Easy’ antispam or spam blocker solution for your organization that supports multiple email domains?

Are you looking for an antispam solution that can be deployed in your production environment in less than 20 minutes?

ESVA Email Security Virtual Appliance (ESVA) is a FOSS based antispam 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 run on VMWare, run 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 ESVA GD official website.

The main components of ESVA are:

• CentOS – Robust operating system cloned by Red Hat
• MailScanner – Antispam package for email gateway systems.
• MailWatch – Web-based administration page for MailScanner
• Postfix – Email System
• SQLgrey – Greylist filtering
• Webmin – Web Based Administration Page CentOS and Postfix Manager
• ClamAV – Open Source Antivirus
• Distributed Checksum Clearinghouses (DCC) and Vipul’s Razor – Bulk Spam Detection
• Pyzor – Spam Detection Network
• SpamAssassin – popular spam filtering package for header, text analysis, Bayesian filtering, DNS blocklists, and filtering database
• FuzzyOCR – Image content and properties Filtering based on fuzzy logic
• MailGraph – Graphic tools for mail statistics

Why do I use ESVA?

The advantages of using ESVA are:

1. free at cost,
2. robust system,
3. filtering precision
4. domain and sender blacklists
5. whitelist domains and senders
6. quarantine and release report (per user or per domain)
7. easy to use and personalized.

I have implemented a custom version of ESVA in our data center since 2007 and it continues to be one of our best antispam solutions. Although, the Bayesian filtering method requires time to build in the SPAM or HAM database. Over time, ESVA’s email filtering becomes more effective in distinguishing between ham and spam compared to some commercial products.

We have 2 ESVA units deployed at Layer 2 running our data center to care for 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 topic filtering
3. No keyword filtering
4. Incorrect 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, plugin, and file path. I am currently building FAQs and customization settings and I hope that anyone using ESVA can benefit from it.

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