On 03/06/16 22:20, Wietse Venema wrote: > Postscreen has postscreen_dnsbl_ttl (fixed time limit) or it uses > the DNS TTL, limited by postscreen_dnsbl_{min,max}_ttl. > > Please see Postfix documentatiom, and report a bug if it is incomplete.
dnsblog(8) states, "Otherwise it replies with the query arguments plus an empty address list and the reply TTL (-1 if unavailable)." It is unclear that this references the negative cache TTL as returned by the SOA record included in an NXDOMAIN response. I had to look at the dnsblog.c source code for this to become clear. Peter