extract from created sendmail.cf file. 
use dnsbl_temp.m4 to auto create this.

#####  $Id: dnsbl_temp.m4,v 8.18.16.1 2003/01/29 18:01:23 reynolds Exp $  #####

# DNS based IP address temporary rejection list probes.bl.reynolds.net.au
R$*			$: $&{client_addr}
R::ffff:$-.$-.$-.$-	$: <?> $(host $4.$3.$2.$1.probes.bl.reynolds.net.au. $: OK $)
R$-.$-.$-.$-		$: <?> $(host $4.$3.$2.$1.probes.bl.reynolds.net.au. $: OK $)
R<?>OK			$: OKSOFAR
R<?>$+			$#error $@ 4.7.1 $: "471 ACCESS TEMPORARILY DENIED to <"$&f"> thru "$&{client_name}" due to /probes/ ; Please see http://bl.reynolds.net.au/probes/"