--- greylist.conf.5.orig        2015-12-28 12:11:18.000000000 +0900
+++ greylist.conf.5     2015-12-28 13:18:13.000000000 +0900
@@ -728,6 +728,9 @@
 which addresses should be looked up, and the answer we should consider
 as a positive hit.
 .PP
+DNSRBL for IPv6 addresses is also available. Some DNSRBLs, such as
+SPAMHAUS, VIRBL and DNSWL, may have entries of IPv6 addresses.
+.PP
 DNSRBL support is only available if enabled through the --enable-dnsrbl
 config flag. Please make sure
 .B milter-greylist(8)