What is it?

rblfilter is a simple tool which can be used to identify mail from RBL-listed sources. You configure it with a list of hosts on which you receive mail, and it extracts the sender's IP address from the "Received:" headers. It is useful when you have no control over the SMTP listener which receives your mail - e.g. at your ISP.

Once configured, it is quite smart about matching the correct Received: header, and it can parse the formats produced by most common mailers. The current implementation is in perl.

You do get a number of false positives by filtering against RBLs, but if you include an exception for messages which are addressed to you personally, you get a very effective yet simple spam filter:

# Keep mail if I am listed as recipient in the headers
* ^TO(brian|btc|b\.candler)

# Filter RBL-listed sources
* ! ?/u/home/brian/bin/rblfilter

Find out more by reading the man page.


The source file is rblfilter.tgz [7K]. This includes the perl script (with embedded perlpod man page) and a regression test file for header parsing.

last updated 29 August 1999