Appendix B. Adding Extra DNSBL Lists

SpamSpector comes supplied with a list of known DNSBL services it can use. In addition, it will periodically connect to the SpamSpector servers to update this list, removing deceased services and adding new ones.

However, sometimes you will want to use a DNSBL service that is not currently supported. To do this, click the "Extra DNSBL Definitions" button on the Advanced pane on the Options dialog; you will be greeted with a text editor window allowing you to edit a file that will contain definitions for any additional DNSBL services you wish to add.

This file must be in a specific format. It comprises entries, one for each DNSBL list, in the following format:

LIST <list code>
NAME <name>
ZONE <zone>
DESCRIPTION <description>

Anything after a # character is a comment, and will be ignored by SpamSpector.

Most of the lines of a DNSBL list definition are self-explanatory. The one thing to note is the <list code> - this should be a sequence of letters that is unique to this DNSBL list. It is advised that you keep DNSBL list codes to seven letters or less.

There are a couple of other types of directive you can optionally add to a DNSBL list definition. The first is SUBSUMED_BY <list-code> - this specifies that this DNSBL service is contained within another DNSBL service, which has the code <list-code> and was defined previously in this file (or was already known to SpamSpector). If the subsuming DNSBL list is selected, the user will not be able to select the subsumed list. For example, the SBL list is subsumed within the list, so the DNSBL defintion for the former is:

NAME Spamhaus SBL
DESCRIPTION The Spamhaus SBL lists known spammers & spam gangs.

By default, any positive response from a DNSBL service is taken to indicate spam. But if you want only certain responses to mean spam, you can specify them with RESULT_CODE <ip-address> directives. For example, the DNSBL service lists spammers, spam-support operations, open relays and dialup hosts; while we want mail from any of the first three to be tagged as spam, we certainly don't want email that came at some point from a dialup host to be spam! So we specify the specific result codes, e.g.:

DESCRIPTION A really big list that contains data from lots of smaller lists.
RESULT_CODE  # verified open relay
RESULT_CODE  # confirmed spam source
RESULT_CODE  # spamware developer/spamvertized site
RESULT_CODE  # insecure formmail.cgi
RESULT_CODE  # open proxy servers

Note that currently only I.P. address-based DNSBL services are supported by SpamSpector - domain-based lists like won't work!

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