A number of RBLs are enabled with the default configuration of SpamAssassin. These are defined in /usr/share/spamassassin/20_dnsbl_tests.cf
. An example definition is shown here:
header RCVD_IN_NJABL eval:check_rbl('njabl', 'dnsbl.njabl.org.') describe RCVD_IN_NJABL Received via a relay in dnsbl.njabl.org tflags RCVD_IN_NJABL net
One set of definitions appears for each RBL configured. Rule definitions are explained in more detail in Chapter 12.
All the rules include a line that sets tflags
to net
. This groups the rules as network tests, and allows SpamAssassin to treat them as a group. There are two main reasons for this. The first is that network tests may take a long time to complete, especially at busy times. SpamAssassin uses a timeout for network tests, but it also applies this timeout in a progressive manner. If most of the network tests have completed, SpamAssassin will not wait for the last tests to complete. Specific details are given in the Mail::SpamAssassin::Conf
main page...