Introduction ============ What is {pmg}? -------------- Email security begins at the gateway, by controlling all incoming and outgoing email messages. {pmg} addresses the full spectrum of unwanted email traffic, focusing on spam and virus detection. {pmg} provides a powerful and affordable server solution to eliminate spam and viruses, and block undesirable content from your email system. All products are self-installing and can be used without deep knowledge of Linux. image::images/Proxmox_Mail_Gateway_Mailprocessing_final_1024.png[] Features -------- [[intro_spam_detection]] Spam detection ~~~~~~~~~~~~~~ {pmg} uses a wide variety of local and network tests to identify spam mail. Here is a short list of used filtering methods: Receiver Verification:: Many of the junk messages reaching your network are emails to non-existent users. {pmg} detects these emails on the SMTP level, before they are transferred to your network. This reduces the traffic to be analyzed for spam and viruses by up to 90% and reduces the working load on your mail servers and scanners. Sender policy framework (SPF):: 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). DNS-based Blackhole List:: 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. SMTP Whitelist:: Exclude senders from SMTP blocking. To prevent all SMTP checks (Greylisting, Receiver Verification, SPF and DNSBL) and accept all emails for 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). Bayesian Filter - Automatically trained statistical filters:: Certain words have a higher probability of occurring in spam emails than in legitimate emails. By being trained to recognize those words, the Bayesian filter checks every email and adjusts the probabilities of it being a spam word or not in its database. This is done automatically. Black- and Whitelists:: Black- and Whitelists 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. Auto-learning algorithm:: {pmg} gathers statistical information about spam emails. This information is used by an auto-learning algorithm, meaning the system becomes smarter over time. Spam URI Real-time Block List (SURBL):: SURBLs are used to detect spam, based on the URIs in the message body (usually websites). 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. Greylisting:: Greylisting an email means that unknown senders are intentionally temporarily rejected. Since temporary failures are part of the specifications for mail delivery, a legitimate server will try to resend the email later on. Spammers, on the other hand, do not queue and reattempt mail delivery. A greylisted email never reaches your mail server and thus your mail server will not send useless "Non Delivery Reports" to spammers. Additionally, greylisted mail is not analyzed by the antivirus and spam-detector engines, which saves resources. + A mail is greylisted if it is the first mail from a sender to a receiver coming from a particular IP network. You can configure which IP addresses belong to the same network, by setting an appropriate netmask for greylisting. SMTP Protocol Tests:: {postfix} is able to do some sophisticated SMTP protocol tests (see `man postscreen`). Most spam is sent out by zombies (malware on compromised end-user computers), and those zombies often try to maximize the amount of mails delivered. In order to do that, many of them violate the SMTP protocol specification and thus can be detected by these tests. Before and After Queue Filtering:: {pmg} can be configured to either accept the mail, by sending a response of '250 OK', and scan it afterwards, or alternatively inspect the mail directly after it has the content and respond with a reject '554' if the mail is blocked by the rule system. These options are known as After Queue and Before Queue filtering respectively (see xref:pmgconfig_mailproxy_before_after_queue[Before and After Queue Scanning]). Configurable NDR policy:: In certain environments, it can be unacceptable to discard an email, without informing the sender about that decision. You can decide whether you want to inform the senders of blocked emails or not. Virus detection ~~~~~~~~~~~~~~~ {pmg} integrates {clamav}, which is an open-source (GPL) 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. Object-Oriented Rule System ~~~~~~~~~~~~~~~~~~~~~~~~~~~ The object-oriented rule system enables custom rules for your domains. It’s an easy but very powerful way to define filter rules by user, domains, time frame, content type and resulting action. {pmg} offers a lot of powerful objects to configure your own custom system. WHO - objects:: Who is the sender or receiver of the email? WHAT - objects:: What is in the email? WHEN - objects:: When was the email received by {pmg}? ACTIONS - objects:: Defines the final actions. Every rule has five categories FROM, TO, WHEN, WHAT and ACTION. Each of these categories can contain several objects and a direction (in, out or both). Options range from simple spam and virus filter setups to sophisticated, highly customized configurations, blocking certain types of emails and generating notifications. Web-based Management Interface ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {pmg} makes email security and filtering simple to manage. The web-based management interface allows you to set up and maintain even a complex mail system with ease. [thumbnail="screenshot/pmg-gui-dashboard.png"] There is no need to install a separate management tool. Any modern internet browser is sufficient. Spam Quarantine ~~~~~~~~~~~~~~~ Identified spam mails can be stored in the user-accessible Spam Quarantine. Thus, users can view and manage their spam mails by themselves. Tracking and Logging ~~~~~~~~~~~~~~~~~~~~ The innovative Proxmox Message Tracking Center tracks and summarizes all available logs. With the web-based and user-friendly management interface, IT admins can easily view and control all functions from a single screen. The Message Tracking Center is fast and powerful. It has been tested on {pmg} sites which process over a million emails per day. All log files from the last 7 days can be queried, and the results are summarized by an intelligent algorithm. The logged information includes: - Arrival of the email - Proxmox filter processing with results - Internal queue to your email server - Status of final delivery DKIM Signing ~~~~~~~~~~~~ {pmg} offers the possibility to optionally sign outgoing emails with xref:pmgconfig_mailproxy_dkim[DKIM]. High Availability with Proxmox HA Cluster ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ To provide a 100% secure email system for your business, we developed Proxmox High Availability (HA) Cluster. The Proxmox HA Cluster uses a unique application-level clustering scheme, which provides extremely good performance. It is quick to set-up and the simple, intuitive management interface keeps resource requirements low. After temporary failures, nodes automatically reintegrate without any operator interaction. LDAP Integration ~~~~~~~~~~~~~~~~ It is possible to query user and group data from LDAP servers. This may be used to build special filter rules, or simply to provide authentication services for the Spam Quarantine GUI. Fetchmail Integration ~~~~~~~~~~~~~~~~~~~~~ {pmg} allows you to fetch mail from other IMAP or POP3 servers. Flexible User Management ~~~~~~~~~~~~~~~~~~~~~~~~ The administration interface uses a role-based access control scheme, using the following roles: Superuser:: This role is allowed to do everything (reserved for user 'root'). Administrator:: Full access to the mail filter setup, but not allowed to alter the network setup. Quarantine Manager:: Is able to view and manage the Spam Quarantine. Auditor:: Has read-only access to the whole configuration, can access logs and view statistics. Helpdesk:: Combines permissions of the 'Auditor' and the 'Quarantine Manager' role. Your benefit with {pmg} ----------------------- * Open-source software * No vendor lock-in * Linux kernel * Fast installation and easy-to-use * Web-based management interface * REST API * Huge, active community * Low administration costs and simple deployment include::getting-help.adoc[]