Email Filters and Utilities

Richard Gooch

If you find any of this software useful, you can donate if you wish by clicking on the donate button below. I've written some email filtering software and utilities that may make your life easier in controlling the flood of spam and viruses that blight your inbox. They are listed below.

A powerful spam filter which I use for blocking spam as well as general email management (such as sorting incoming email into different folders so that high-traffic email lists don't flood my normal inbox). This filter was originally written by Lars Wirzenius, but I've heavily modified it. The basic method used in this filter to combat spam is to bounce messages from people I don't know, requiring them to resend their message with a password (the bounce message tells them the password). This is a personal filter, not a system-wide filter.
milter-dnsrbl, a sendmail milter which allows an email administrator to reject messages which originate from, or are relayed via, an MTA which is listed in a DNS Real-time Black List (DNSRBL). Features include:
- reject a message with a 44x (temporary) error
- reject a message with a 55x (permanent) error
- discard a message (silently)
- accept a message, but insert a tag (header line)
- stall the connection indefinately (until sender times out)
- stall the connection for a specified time
- check Received: header lines for IP addresses of previous relay machines
- wildcard matches of A record values
It is currently packaged as part of my email utilities.
milter-regexp, a sendmail milter which allows an email administrator to reject messages based on regular expression matches. Features include:
- reject a message with a 44x (temporary) error
- reject a message with a 55x (permanent) error
- discard a message (silently)
- accept a message, but insert a tag (header line)
- redirect the message to a different destination
- accept the message with no changes
- stall the connection for a specified time
- support for per-recipient configuration files (at the discretion of the system administrator)
It is currently packaged as part of my email utilities.
milter-size, a sendmail milter which allows an email administrator to reject messages of a specified size range. It is currently packaged as part of my email utilities. It also can send message sizes over a UDP socket, which can be used for later analysis or real-time display (such as a histogram of sizes).