NAME

URIDNSBL - look up URLs against DNS blocklists

SYNOPSIS

  loadplugin    Mail::SpamAssassin::Plugin::URIDNSBL
  uridnsbl      URIBL_SBLXBL    sbl-xbl.spamhaus.org.   TXT

DESCRIPTION

This works by analysing message text and HTML for URLs, extracting the domain names from those, querying their NS records in DNS, resolving the hostnames used therein, and querying various DNS blocklists for those IP addresses. This is quite effective.

CONFIGURATION

uridnsbl NAME_OF_RULE dnsbl_zone lookuptype

Specify a lookup. NAME_OF_RULE is the name of the rule to be used, dnsbl_zone is the zone to look up IPs in, and lookuptype is the type of lookup (TXT or A). Note that you must also define a body-eval rule calling check_uridnsbl() to use this.

Example:

 uridnsbl        URIBL_SBLXBL    sbl-xbl.spamhaus.org.   TXT
 body            URIBL_SBLXBL    eval:check_uridnsbl('URIBL_SBLXBL')
 describe        URIBL_SBLXBL    Contains a URL listed in the SBL/XBL blocklist

urirhsbl NAME_OF_RULE rhsbl_zone lookuptype

Specify a RHSBL-style domain lookup. NAME_OF_RULE is the name of the rule to be used, rhsbl_zone is the zone to look up domain names in, and lookuptype is the type of lookup (TXT or A). Note that you must also define a body-eval rule calling check_uridnsbl() to use this.

An RHSBL zone is one where the domain name is looked up, as a string; e.g. a URI using the domain foo.com will cause a lookup of foo.com.uriblzone.net. Note that hostnames are stripped from the domain used in the URIBL lookup, so the domain foo.bar.com will look up bar.com.uriblzone.net, and foo.bar.co.uk will look up bar.co.uk.uriblzone.net.

If a URI consists IP address instead of a hostname, the IP address is looked up (using the standard reversed quads method) in each rhsbl_zone.

Example:

  urirhsbl        URIBL_RHSBL    rhsbl.example.org.   TXT

urirhssub NAME_OF_RULE rhsbl_zone lookuptype subtest

Specify a RHSBL-style domain lookup with a sub-test. NAME_OF_RULE is the name of the rule to be used, rhsbl_zone is the zone to look up domain names in, and lookuptype is the type of lookup (TXT or A).

subtest is the sub-test to run against the returned data. The sub-test may either be an IPv4 dotted address for RHSBLs that return multiple A records or a non-negative decimal number to specify a bitmask for RHSBLs that return a single A record containing a bitmask of results.

Note that, as with urirhsbl, you must also define a body-eval rule calling check_uridnsbl() to use this.

Example:

  urirhssub   URIBL_RHSBL_4    rhsbl.example.org.   A    127.0.0.4
  urirhssub   URIBL_RHSBL_8    rhsbl.example.org.   A    8

uridnsbl_timeout N (default: 2)

Specify the maximum number of seconds to wait for a result before giving up on the lookup. Note that this is in addition to the normal DNS timeout applied for DNSBL lookups on IPs found in the Received headers.

uridnsbl_max_domains N (default: 20)

The maximum number of domains to look up.

uridnsbl_skip_domain domain1 domain2 ...

Specify a domain, or a number of domains, which should be skipped for the URIBL checks. This is very useful to specify very common domains which are not going to be listed in URIBLs.