Re: Trying to use RBL Overrides to whitelist IP Range.

Oops, my mistake. sorry.

Please try below steps instead to avoid Amavisd+SpamAssassin scanning.

1) Append port '10026' in Amavisd config file (/etc/amavisd/amavisd.conf), parameter "$inet_socket_port". For example:

$inet_socket_port = [10024, 10026];

2) Add below settings in Amavisd config file:

$interface_policy{'10026'} = 'BYPASS';

$policy_bank{'BYPASS'} = {
   originating => 1,
   bypass_spam_checks_maps   => [1],  # don't spam-check this mail
   bypass_banned_checks_maps => [1],  # don't banned-check this mail
   bypass_header_checks_maps => [1],  # don't header-check this mail  
};

3) Restart Amavisd service.
4) Update your rbl_override file, use port 10026 instead of 10025. For example:

68.178.252.0/24 FILTER smtp-amavis:[127.0.0.1]:10026

NOTE: If IP range doesn't work, try single IP address instead.