Installation manual

42
of the program (see chapter Antispam engine parameter setup ).
dnsbl_list
List of DNSBL servers to be used in checks of domains and IP adrresses in the email body.
Format of entry is as follows: dnsbl_list=server:response:offset,server2:response2:offset2,...
Meaning parameters used:
1) server - DNSBL server name
2) response - DNSBL server response if IP address/domain was found (standard responses are
127.0.0.2, 127.0.0.3, 127.0.0.4., etc.). This parameter is optional, and if not set, all answers will
be considered.
3) offset - value from 0 to 100. Influences overall spam score. Standard value is 100, i.e. in case
of a positive check the message is assigned the spam score of 100 and is evaluated as spam.
Negative values lower the overall spam score of a message. Expect the 0 value also with
messages from senders in the approvedsenders file and the value 100 with messages from
senders in the blockedsenders file (see below).
DNSBL checks can have negative influence on server performance due to the fact that every
domain/IP address from the message body is checked against all defined DNSBL servers and
every single check requires processing a DNS server request. You can reduce the impact on
system resources by deploying a DNS cache server for this purpose. For the same reason the
non-routable IP addresses (10.x.x.x, 127.x.x.x, 192.168.x.x) are also omitted from DNSBL checks.
Example 1: dnsbl_list=ent.adbl.org
DNSBL check is performed against the ent.adbl.org server. If there is a positive, the message
will be assigned the default offset 100 (it will be marked as spam).
Example 2: dnsbl_list=ent.adbl.org::60
DNSBL check is performed using the ent.adbl.org server. If the check is positive, the message
will be assigned an offset of 60 which increases its overall spam score.
Example 3: dnsbl_list=bx9.dbl.com::85, list.dnb.org:127.0.0.4:35, req.gsender.org::-75
DNSBL check is performed using the defined servers (from left to right). If there is a positive
check on bx9.dbl.com, the offset of 85 will be added. If the check on list.dnb.org will be positive,
giving a response of 127.0.0.4 an offset of 35 will be used. No offset will be applied in cases of
answers other than 127.0.0.4. If a check is positive on req.gsender.org the spam score will be
decreased by 75 points (negative value).
home_country_list
List of countries, that will be considered "home". Messages routed through a country not on this
list will be evaluated using more strict rules (higher spam score will be applied). Entry format for
countries is their two character code in compliance with ISO 3166.
home_language_li
st
List of preferred languages - i.e. languages that are the most used in your email messages. Such
messages will be evaluated using less strict rules (lower spam score). Entry format for
languages is their two character code in compliance with ISO 639.
custom_rules_list
Allows you to define custom lists of rules and store each list to an individual file. Each rule is
stored on a separate line in the file in the following format:
Phrase, Type, Confidence, CaseSensitivity
Phrase - any text, must not contain commas (,)
38