spam

This article explains how you can download additional SpamAssassin rulesets resp. automatically update these rulesets with a shell script called RulesDuJour. These additional rulesets can increase your spam recognition rate dramatically. Most of the rulesets that RulesDuJour supports can be found on the SA Rules Emporium web site.

This article describes how to integrate DSPAM with embedded ClamAV into a mail server based on Postfix featuring virtual users and domains, i.e. users and domains that are in a MySQL database. DSPAM is a scalable and open-source content-based spam filter. The setup shown here is suitable for Debian Etch servers.

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.

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.

A blacklist usually refers to a list of email or IP addresses known to send spam emails or some other type of unsolicited messages. Such lists are currently used by mail servers for filtering incoming emails 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.

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.

Fetchmail is a program for retrieving emails from remote servers. Imagine you have five email accounts on five different servers. Of course, you do not want to connect to each of them to get your emails. This is where fetchmail comes into play. If you have a user account on a Linux server, you can make fetchmail download emails from remote servers and put them into just one mailbox (the one of your Linux user), from where you can retrieve them with your email client (e.g. Thunderbird or Outlook).

Simple how-to for installing and configuring policyd-weight policy daemon. Policyd-weight sits inline with Postfix and can reject mails before the data transaction. This is great for quickly IDing spammers and rejecting them before soaking up bandwidth and processing via spamassassin. How-to is geared towards Gentoo Linux, but can be easily applied to others.

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.

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).