Email Classification (Incl. Spam Classification) With POPFile On Ubuntu Feisty Fawn

This article shows how you can install and use POPFile to classify incoming emails on an Ubuntu Feisty Fawn desktop. It is a POP3 proxy that fetches your mails from your mail server, classifies them and passes them on to your email client. Of course, POPFile must be trained to properly classify emails.

Filtering PDF-/XLS-/Image-Spam With ClamAV (And ISPConfig) On Debian/Ubuntu

There is currently a lot of spam where the spam "information" is attached as .pdf or .xls files, sometime also hidden inside a .zip file. While these spam mails are not easy to catch with e.g. SpamAssassin or a Bayes filter, the ClamAV virus scanner can catch them easily when it is fed with the correct signatures as ClamAV is built to scan mail attachments.

How to Avoid Being Blacklisted

A blacklist usually refers to a list of e-mail or IP addresses known to send spam e-mails or some other type of unsolicited messages. Such lists are currently used by mail servers for filtering incoming e-mails and blocking the ones listed, in order to improve mail security and integrity. The blacklist is also the opposite of what is called a whitelist.

Introduction to Antispam Practices 

Competitive Antispam products, proper legislation, efforts towards a better user education, it has all been tried in order to stop spam. However, unsolicited emails keep consuming the space and time of all email users. Moreover, spam messages can be the cause of serious virus and spyware outbreaks, while others “phish” for sensitive information like bank accounts and passwords.

Virtual Users And Domains With Postfix, Courier And MySQL (Debian Etch)

This document describes how to install a mail server based on Postfix that is based on virtual users and domains, i.e. users and domains that are in a MySQL database. I'll also demonstrate the installation and configuration of Courier (Courier-POP3, Courier-IMAP), so that Courier can authenticate against the same MySQL database Postfix uses.

How To Block Spam Before It Enters The Server (Postfix)

The last few weeks have seen a dramatic increase in spam (once again). Estimates say that spam makes now up for 80 - 90% of all emails, and many mail servers have difficulties in managing the additional load caused by the latest spam, and spam filters such as SpamAssassin do not recognize large parts of that spam as they did before. Fortunately, we can block a big amount of that spam at the MTA level, for example by using blacklists, running tests on the sender and recipient domains, etc. An additional benefit of doing this is that it lowers the load on the mail servers because the (resource-hungry) spamfilters have to look at less emails.

Virtual Users And Domains With Postfix, Courier And MySQL (Ubuntu 6.10 Edgy Eft)

This document describes how to install a mail server based on Postfix that is based on virtual users and domains, i.e. users and domains that are in a MySQL database. I'll also demonstrate the installation and configuration of Courier (Courier-POP3, Courier-IMAP), so that Courier can authenticate against the same MySQL database Postfix uses. The resulting Postfix server is capable of SMTP-AUTH and TLS and quota. In addition to that, this tutorial covers the installation of Amavisd, SpamAssassin and ClamAV so that emails will be scanned for spam and viruses.

Integrating amavisd-new Into Postfix For Spam- And Virus-Scanning

This article shows how to integrate amavisd-new into a Postfix mail server for spam- and virus-scanning. amavisd-new is a high-performance interface between MTAs such as Postfix and content checkers: virus scanners, and/or SpamAssassin. We will use ClamAV for virus scanning and SpamAssassin for spam scanning in this tutorial.

How To Implement SPF In Postfix

This tutorial shows how to implement SPF (Sender Policy Framework) in a Postfix 2.x installation. The Sender Policy Framework is an open standard specifying a technical method to prevent sender address forgery. There are lots of SPF extensions and patches available for Postfix, but most require that you recompile Postfix. Therefore we will install the postfix-policyd-spf-perl package from openspf.org which is a Perl package and can be implemented in existing Postfix installations (no Postfix compilation required).

Prevent Phishing with Mutual Authentication

Phishing is a man-in-the-middle attack. While many people think using time-bound, one-time passwords will solve the problem, they are wrong as attacks will just become automated. What is required is strong mutual authentication - authentication of the host to the user as well as the user to the host. This article demonstrates how to do that using open-source software from WiKID.