Example 4

A domain administrator for quuux.com wants to deny all email from a pool of MTAs that have been confirmed in sending spam.

+-------------+---------------+----------------+----------------------+--------------+--------+
| sender_name | sender_domain | src            | mta_fqdn             | dest_address | policy |
+-------------+---------------+----------------+----------------------+--------------+--------+
| *           | *             | *              | *.spammers.com       | *@quuux.com  |      2 | 
+-------------+---------------+----------------+----------------------+--------------+--------+

This disallows all delivery for any email server underneath the subdomain spammers.com, ie: mta-a.spammers.com, mta-b.spammers.com, etc.