+PP/17 Update configure.default to handle IPv6 localhost better.
+ Patch by Alain Williams (plus minor tweaks).
+ Bugzilla 880.
+
+PP/18 OpenSSL made graceful with empty tls_verify_certificates setting.
+ This is now consistent with GnuTLS, and is now documented: the
+ previous undocumented portable approach to treating the option as
+ unset was to force an expansion failure. That still works, and
+ an empty string is now equivalent.
+
+PP/19 Renamed DNSSEC-enabling option to "dns_dnssec_ok", to make it
+ clearer that Exim is using the DO (DNSSEC OK) EDNS0 resolver flag,
+ not performing validation itself.
+