Email Security

Best Open Source Secure Email Gateway Packages

Secure Email Gateways or Email security gateways are gateways designed to filter mail traffic. Some mail providers and other types of organizations implement this solution to fight attacks like phishing, email-borne attacks, viruses, malwares and more attacks which can be filtered by an email gateway, but it also can prevent information leak by infidel members of the organization, etc. It is a controller of mail content which rules according to the specified rules and policies.

Email Secure Gateways are available as a cloud service, as virtual appliance, locally at the mail server and there are both software and hardware solutions but this article focuses on 5 Email Security Gateways: MailScanner, MailCleaner, Proxmox, Hermes Secure Email Gateway and OrangeAssasin, all them include free versions while some offer additional paid versions with extra features.

MailScanner

MailScanner is among the most popular open source solutions for secure email gateways. It prevents attacks through spam using Spamassassin, viruses integrating third party antivirus such as Clam AV, phishing, malware and more.

MailScanner can be installed as gateway or integrated with mail gateways such as MailCleaner mentioned below in this article.

Installing MailScanner is pretty simple, you can get packages for Debian and Red hat based Linux distributions at https://github.com/MailScanner/v5/tree/master/builds, it is highly recommended to install it on a clean OS. Around 80 billion of emails are supervised by MailScanner monthly, it shows high performance on low resources hardware too. A comprehensive guide of configuration options for MailScanner to understand all its fueatures is available at https://www.mailscanner.info/MailScanner.conf.index.html.

MailCleaner

MailCleaner is another open source alternative for email secure gateway, Like the rest of solutions it features antispam, antivirus protection, quarantine, newsletter detection and web based administration interface.

MailCleaner is ready to be installed on any virtualization platform, it works as MX record for the domain name.  It is built on Debian 8 and uses MailScanner which heads this list. Like the rest of gateways it offers an intuitive web interface which unificates all functionalities. Out of the community edition, MailCleaner offers paid addons (SpamHaus Professional RBLs and Kaspersky Antivirus).The paid version offers automatic updates every 15 minutes, access to professional anti spam rules and antivirus, while the free version offers free ClamAV and basic rules. The paid version also features an IP list to detect newsletter, additionally to the rules included in the free version. RBL and UriBL also differ from the free to paid version, the paid version includes a Byesian automatically updated filter, managed setup , addons and premium support, while the community edition has support only through the forum. Still on its free version MailCleaner is among the best Open Source solutions in the market.

MailCleaner email secure gateway can be downloaded from https://www.mailcleaner.org/download/.

Proxmox Mail Gateway

Proxmox Mail Gateway is another market leading technology to filter mail threats. It is  very user friendly with  a web management interface. It is Debian and Ubuntu based virtualized system and can be downloaded from https://www.proxmox.com/en/downloads.

Proxmox works through many methods which include receiver corroboration to confirm the email receiver is a real existent user. It also checks SPF (Sender Policy Framework) in order to validate the sender and prevent email forgery. DNS-based Blackhole List (DNSBL) is another method used by Proxmox which checks for blacklisted IP addresses known for spammy activity. It also features a SMTP whitelist which allows you to filter by email address, domain name, regular expressions and IP address, black and white lists are widely used in Proxmox and all other options mentioned in this article. It also can detect problematic domains through SURBL.

Auto Learning algorithms and a Beyesian filter complete this software adding development intelligence. Customizing Proxmox is pretty easy with an object rule system which makes it easy to filter users, domains, time frames, content and measures to be taken according to scan results. Proxmox is, together with MailScanner, one of the best open source solutions in the market for Mail Secure Gateway.

Hermes Secure Email Gateway

Hermes Unified Secure Email Gateway is another Open Source solution based on Ubuntu Server. While Hermes Secure Email Gateway is open source, it is offered in 3 formats:

Hermes SEG Community: this is the free version without support (support is available through forum), without warranty and without possibility to self host all features.
Hermes SEG Pro:
this license allows you to self host all features.
Hermes SEG SaaS:
this service includes SEG Pro + a management service.

Hermes Unified Secure Email Gateway helps to fight virus, malwares, spam and other threats such as mail forgery aided by SPF, DKIM (DomainKeys Identified Mail), DMARC (Domain-based Message Authentication). The “Unified” on its name refers to the integration of tools such as Postfix, SpamAssasin, ClamAV and others whose management is unified through a unique web interface similarly to Proxmox. Hermes can be installed locally or as a cloud solution. You can get the community edition for free at https://github.com/deeztek/Hermes-Secure-Email-Gateway.

OrangeAssasin

OrangeAssasin is the last of this list, another free open source secure email gateway which supports incorporating plugins with additional features. Orange Assassin portrays itself as an upgraded replacement for SpamAssasin. Among all products listed in this article Orange Assassin is the less empirically backed (the less used).

You can get OrangeAssasin for free at https://github.com/SpamExperts/OrangeAssassin.

Conclusion:

All products mentioned are almost the same and friendly users without major differences between them. Considering 90% of mails are spam incorporating a Secure Email Gateway solution is a must if you plan to setup a mail server. All solutions numerated here are available for virtualized environments and can be tested without risks. From all solutions mentioned above probably the most recommendable by the community are MailScanner and MailCleaner.

I hope you found this article on Best Open Source Secure Email Gateway Packages useful.

About the author

Ivan Vanney

Ivan Vanney

Ivan Vanney has over 2 years as writer for LinuxHint, he is co-founder of the freelance services marketplace GIGopen.com where he works as a sysadmin.