EFA or “Email Filter Appliance” is one of the most popular Opensource application for filtering Email Spam & viruses. It is a community driven project, it combines renowned open source software’s to build a powerful Spam Filtering Platform. EFA includes well known anti spam programs like MailScanner, SpamAssassin, ClamAV, MailWatch, Razor, Pyzor, DCC, SQL grey and image cerberus for its various spam detection techniques, you can find detail information here.
In these series of tutorials, I will try to explain, Ins and out’s of EFA, How can we get the most outcome from it, by properly configuring and tuning various settings and deploying it at appropriate places.
We will discuss about the followings :
1. EFA Deployment Scenarios
2. Installing EFA On CentOS
3. EFA as The Incoming Email Filter
4. EFA as The Outgoing Email Filter
5. Configuration Details.
E.F.A Deployment Scenarios
EFA is a Gateway Appliance, we can deploy EFA on the edge of the Mail Servers, All Mail Servers will receive mail after it has been scanned by EFA. The scenario is the same during Inbound and outbound time. Email filter appliances deployment depends on a number of factors like, current infrastructure, resource availability, investment and so on. In my another blog post, I have described some common scenarios for spam-filter deployment. EFA fits in all those environments. EFA can be installed on physical hardware Or on a virtual private server (VPS) and can be used on premise and in the cloud also. In summery, I depicted the placement of EFA in the image below.
At every scenario, EFA will receive mail from the internet and after scanning, it will deliver the clean mail to the primary mailbox server. If our email load is high, we can configure multiple EFA appliance to distribute the load to multiple appliances. To learn about incoming mail load balancing you can read my other blog post here.