+PH/06 In both GnuTLS and OpenSSL, an expansion of tls_privatekey that results
+ in an empty string is now treated as unset.
+
+PH/07 There is a new log selector called sender_verify_fail, which is set by
+ default. If it is unset, the separate log line that gives details of a
+ sender verification failure is not written. Log lines for the rejection
+ of SMTP commands (e.g. RCPT) contain just "sender verify failed", so some
+ detail is lost.
+