Blocked mail from ips MTA option

MAIL FROM domain blocking by IP address
The introduction of DNS wildcard entries in the COM and ORG top level domains which occurred in September 2003 had severely limited the effectiveness of the   channel option. As of the 6.1-0.01 release of the MTA, the  channel option code was modified to address this. When the DNS returns one or more A records (which would normally be considered a "success" and the message would be allowed in), their values are compared against the domain literals specified by the  MTA option. If a match is found, then the domain is considered to be invalid. Thus in order to restore useful behavior to the  channel option, the current correct setting of this option is: blocked_mail_from_ips=&#x5b;64.94.110.11&#x5d;

See also:
 * DNS lookup MTA options
 * mailfromdnsverify Option