Introduction ============ What is {pmg}? -------------- E-mail security begins at the gateway by controlling all incoming and outgoing e-mail messages. {pmg} addresses the full spectrum of unwanted e-mail traffic, focusing spam and virus detection. {pmg} provides a powerful and affordable server solution to eliminate spam, viruses and blocking undesirable content from your e-mail 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 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):: Sender Policy Framework (SPF) is an open standard for validating emails and to prevent 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 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) Bayesian Filter - Automatically trained statistical filters:: Some particular words have a higher probability of occurring in spam emails rather than in legitimate emails. By being trained to recognize those words, the Bayesian 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. Autolearning algorithm:: {pmg} gathers statistical information about spam emails. This information is used by an autolearning algorithm, so the system becomes smarter over time. Spam Uri Realtime BlockList (SURBL):: 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. 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 get 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 mutli-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 e-mail? WHAT - objects:: What is in the e-mail? WHEN - objects:: When is the e-mail received by {pmg}? ACTIONS - objects:: Defines the final actions. Every rule has five categories FROM, TO, WHEN, WHAT and ACTION. Every 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 e-mails and generating notifications. Web-based Management Interface ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {pmg} makes email security and filtering simple to manage. A web-based management interface allows you to setup and maintain even a complex mail setup with ease. [thumbnail="pmg-gui-dashboard.png"] There is no need to install a separate management tool. Every modern internet browser is sufficient. Spam Quarantine ~~~~~~~~~~~~~~~ Identified Spam mails can be stored to the user-accessible Spam quarantine. Users can so 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 overview and control all functions from a single screen. The Message Tracking Center is very fast and powerful, tested on {pmg} sites processing over a million emails per day. All different 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 filtering 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. Fast set-up within minutes and a simple, intuitive management keep resource needs 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 just 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 mail filter setup, but not allowed to change 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[]