dnsbl plugin

This plugin looks up the connecting IP address in an IP blocklist. Mails found to be in the blocklist are rejected.

Configuration

This plugins uses the following files:

dnsbl.zones - Contains a list of zones to query, one per line.

dnsbl.ini - INI format with options described below:

• zones
  A comma or semi-colon list of zones to query. It will be merged with any lists in dnsbl.zones.
• periodic_checks
  If enabled, this will check all the zones every n minutes. The minimum value that will be accepted here is 5. Any value less than 5 will cause the checks to be run at start-up only.
  The checks confirm that the list is responding and that it is not listing the world. If any errors are detected, then the zone is disabled and will be re-checked on the next test. If a zone subsequently starts working correctly then it will be re-enabled.
• enable_stats
  To use this feature you must have installed the 'redis' module and have a redis server running.
  When enabled, this will record several list statistics to redis.
  It will track the total number of queries (TOTAL) and the average response time (AVG_RT) and the return type (e.g. LISTED or ERROR) to a redis hash where the key is 'dns-list-stat:zone' and the hash field is the response type.
  It will also track the positive response overlap between the lists in another redis hash where the key is 'dns-list-overlap:zone' and the hash field is the other list names.
  Example:

  redis 127.0.0.1:6379> hgetall dns-list-stat:zen.spamhaus.org
    1) "TOTAL"
    2) "23"
    3) "ENOTFOUND"
    4) "11"
    5) "LISTED"
    6) "12"
    7) "AVG_RT"
    8) "45.5"
    redis 127.0.0.1:6379> hgetall dns-list-overlap:zen.spamhaus.org
    1) "b.barracudacentral.org"
    2) "1"
    3) "bl.spamcop.net"
    4) "1"
    5) "TOTAL"
    6) "1"
    

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• stats_redis_host
  In the form of host:port this option allows you to specify a different host on which redis runs.
• reject (default: true)
  Reject connections from IPs that are blacklisted. Setting this to false makes dnsbl informational. reject=false is best used in conjunction with plugins like karma that employ a scoring engine to make choices about message delivery.
• search: (default: first)
  first: consider first DNSBL response conclusive. End processing. all: process all DNSBL results