Features

ClamAV is an open-source antivirus engine designed for detecting Trojans, viruses, malware and other malicious threats. It provides a high performance multi-threaded scanning daemon, command line utilities for on demand file scanning, and an intelligent tool for automatic signature updates.

Proxmox Mail Gateway uses a wide variety of local and network tests to identify spam signatures. This makes it harder for spammers to identify one aspect which they can craft their messages to work around. Every single e-mail will be analyzed and get a spam score assigned. The systems attempt to optimize the efficiency of the rules that are run in terms of minimizing the number of false positives and false negatives.

Many of the junk messages reaching your network are emails to non-existent users. Proxmox Mail Gateway detects these emails on SMTP level, which means before they are transferred to your networks. This reduces the traffic to be analyzed for spam and viruses up to 90% and reduces the working load on your mail servers and scanners.

Sender Policy Framework (SPF) is an open standard for validating emails and preventing sender IP address forgery. SPF allows the administrator of an Internet domain to specify which computers are authorized to send emails with a given domain by creating a specific SPF record in the Domain Name System (DNS).

A DNS-based Blackhole List (DNSBL) is a means by which an Internet site may publish a list of IP addresses, in a format which can be easily queried by computer programs on the internet. The technology is built on top of the Domain Name System. DNSBLs are used to publish lists of addresses linked to spamming.

Exclude senders from SMTP blocking. To prevent all SMTP checks (Greylisting, Receiver Verification, SPF and RBL) and accept all e-mails for the analysis in the filter rule system, you can add the following to this list: Domains (Sender/Receiver), Mail address (Sender/Receiver), Regular Expression (Sender/Receiver), IP address (Sender), IP network (Sender)

Block- and Welcomelists are an access control mechanism to accept, block, or quarantine emails to recipients. This allows you to tune the rule-system by applying different objects like domains, email address, regular expression, IP Network, LDAP Group, and others.

Greylisting means that your system temporarily rejects an email from a sender your system does not recognize. Since temporary failures are built into the RFC specifications for mail delivery, a legitimate server will try to resend the email later on. This is an effective method because spammers do not queue and reattempt mail delivery as a regular Mail Transport Agent would normally do. Greylisting can reduce e-mail traffic up to 50%. A greylisted email never reaches your mail server and thus your mail server will not send useless "Non Delivery Reports" to spammers.

SURBLs are used to detect spam based on message body URIs (usually web sites). This makes them different from most other Real-time Blocklists, because SURBLs are not used to block spam senders. SURBLs allow you to block messages that have spam hosts which are mentioned in message bodies.

The Proxmox HA Cluster consists of a master and several nodes (minimum of one node). All configuration is done on the master and then synchronized to all cluster nodes over a VPN tunnel.

Benefits of Proxmox HA Cluster:

• Centralized configuration management
• Fully redundant data storage
• High availability
• High performance
• Unique application level clustering scheme
• Cluster setup is done within minutes
• Nodes automatically reintegrate after temporary failures - without any operator interaction.

With MX records it is simple to set up a high performance load balanced mail cluster. You just have to define two MX records with the same priority.

To start, you need two working Proxmox Mail Gateways, each having its own IP address. Then you define your MX records. You will receive mails on both hosts - more or less load-balanced, using Round-robin scheduling. Round-robin (RR) is a scheduling algorithm which alternates between systems. If one host fails the other is used.

Note: It is always very useful to add reverse lookup entries (PTR records) for those hosts. Many e-mail systems nowadays reject emails from hosts without valid PTR records.

If you have many domains, it is possible to use one MX record per domain and multiple address records. This way you can add one DNS MX record to all your domains, which points to multiple IP Addresses, saving you the burden of adding multiple records to many domains.