This should fix bug 7338, but the related commits were backported to
the 3.4 branch as part of SpamAssassin bug 7231 (comment 13).

--- a/lib/Mail/SpamAssassin/Dns.pm	2017/04/16 06:19:30	1791572
+++ b/lib/Mail/SpamAssassin/Dns.pm	2017/04/16 07:28:59	1791573
@@ -171,7 +171,7 @@
   if (substr($rule, 0, 2) eq "__") {
     # don't bother with meta rules
   } elsif ($answer->type eq 'TXT') {
-    # txtdata returns a non- zone-file-format encoded result, unlike rdatastr;
+    # txtdata returns a non- zone-file-format encoded result, unlike rdstring;
     # avoid space-separated RDATA <character-string> fields if possible,
     # txtdata provides a list of strings in a list context since Net::DNS 0.69
     $log = join('',$answer->txtdata);
@@ -215,11 +215,13 @@
 
   my $qname = $question->qname;
 
-  # txtdata returns a non- zone-file-format encoded result, unlike rdatastr;
+  # txtdata returns a non- zone-file-format encoded result, unlike rdstring;
   # avoid space-separated RDATA <character-string> fields if possible,
   # txtdata provides a list of strings in a list context since Net::DNS 0.69
   #
+  # rdatastr() is historical/undocumented, use rdstring() since Net::DNS 0.69
   my $rdatastr = $answer->UNIVERSAL::can('txtdata') ? join('',$answer->txtdata)
+               : $answer->UNIVERSAL::can('rdstring') ? $answer->rdstring
                                                     : $answer->rdatastr;
   if (defined $qname && defined $rdatastr) {
     my $qclass = $question->qclass;
@@ -267,8 +269,13 @@
     my $answ_type = $answer->type;
     # TODO: there are some CNAME returns that might be useful
     next if ($answ_type ne 'A' && $answ_type ne 'TXT');
-    # skip any A record that isn't on 127/8
-    next if ($answ_type eq 'A' && $answer->rdatastr !~ /^127\./);
+    if ($answ_type eq 'A') {
+      # Net::DNS::RR::A::address() is available since Net::DNS 0.69
+      my $ip_address = $answer->UNIVERSAL::can('address') ? $answer->address
+                                                          : $answer->rdatastr;
+      # skip any A record that isn't on 127.0.0.0/8
+      next if $ip_address !~ /^127\./;
+    }
     for my $rule (@{$rules}) {
       $self->dnsbl_hit($rule, $question, $answer);
     }
@@ -284,11 +291,13 @@
 sub process_dnsbl_set {
   my ($self, $set, $question, $answer) = @_;
 
-  # txtdata returns a non- zone-file-format encoded result, unlike rdatastr;
+  # txtdata returns a non- zone-file-format encoded result, unlike rdstring;
   # avoid space-separated RDATA <character-string> fields if possible,
   # txtdata provides a list of strings in a list context since Net::DNS 0.69
   #
-  my $rdatastr = $answer->UNIVERSAL::can('txtdata') ? join('',$answer->txtdata)
+  # rdatastr() is historical/undocumented, use rdstring() since Net::DNS 0.69
+  my $rdatastr = $answer->UNIVERSAL::can('txtdata')  ? join('',$answer->txtdata)
+               : $answer->UNIVERSAL::can('rdstring') ? $answer->rdstring
                                                     : $answer->rdatastr;
 
   while (my ($subtest, $rule) = each %{ $self->{dnspost}->{$set} }) {
--- a/lib/Mail/SpamAssassin/Plugin/AskDNS.pm	2017/04/16 06:19:30	1791572
+++ b/lib/Mail/SpamAssassin/Plugin/AskDNS.pm	2017/04/16 07:28:59	1791573
@@ -140,7 +140,7 @@
 multiple character-strings (as defined in Section 3.3 of [RFC1035]), these
 strings are concatenated with no delimiters before comparing the result
 to the filtering string. This follows requirements of several documents,
-such as RFC 5518, RFC 4408, RFC 4871, RFC 5617.  Examples of a plain text
+such as RFC 5518, RFC 7208, RFC 4871, RFC 5617.  Examples of a plain text
 filtering parameter: "127.0.0.1", "transaction", 'list' .
 
 A regular expression follows a familiar perl syntax like /.../ or m{...}
@@ -539,7 +539,7 @@
     @answer = ( undef );
   }
 
-  # NOTE:  $rr->rdatastr returns the result encoded in a DNS zone file
+  # NOTE:  $rr->rdstring returns the result encoded in a DNS zone file
   # format, i.e. enclosed in double quotes if a result contains whitespace
   # (or other funny characters), and may use \DDD encoding or \X quoting as
   # per RFC 1035.  Using $rr->txtdata instead avoids this unnecessary encoding
@@ -566,19 +566,26 @@
       # special case, no answer records, only rcode can be tested
     } else {
       $rr_type = uc $rr->type;
-      if ($rr->UNIVERSAL::can('txtdata')) {  # TXT, SPF
-        # join with no intervening spaces, as per RFC 5518
+      if ($rr_type eq 'A') {
+        # Net::DNS::RR::A::address() is available since Net::DNS 0.69
+        $rr_rdatastr = $rr->UNIVERSAL::can('address') ? $rr->address
+                                                      : $rr->rdatastr;
+        if ($rr_rdatastr =~ m/^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\z/) {
+          $rdatanum = Mail::SpamAssassin::Util::my_inet_aton($rr_rdatastr);
+        }
+
+      } elsif ($rr->UNIVERSAL::can('txtdata')) {
+        # TXT, SPF: join with no intervening spaces, as per RFC 5518
         if ($txtdata_can_provide_a_list || $rr_type ne 'TXT') {
           $rr_rdatastr = join('', $rr->txtdata);  # txtdata() in list context!
         } else {  # char_str_list() is only available for TXT records
           $rr_rdatastr = join('', $rr->char_str_list);  # historical
         }
       } else {
-        $rr_rdatastr = $rr->rdatastr;
-        if ($rr_type eq 'A' &&
-            $rr_rdatastr =~ m/^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\z/) {
-          $rdatanum = Mail::SpamAssassin::Util::my_inet_aton($rr_rdatastr);
-        }
+        # rdatastr() is historical, use rdstring() since Net::DNS 0.69
+        $rr_rdatastr = $rr->UNIVERSAL::can('rdstring') ? $rr->rdstring
+                                                       : $rr->rdatastr;
+        utf8::encode($rr_rdatastr)  if utf8::is_utf8($rr_rdatastr);
       }
     # dbg("askdns: received rr type %s, data: %s", $rr_type, $rr_rdatastr);
     }
--- a/lib/Mail/SpamAssassin/Plugin/URIDNSBL.pm	2017/04/16 06:19:30	1791572
+++ b/lib/Mail/SpamAssassin/Plugin/URIDNSBL.pm	2017/04/16 07:28:59	1791573
@@ -1009,10 +1009,9 @@
     dbg("uridnsbl: complete_a_lookup aborted %s", $ent->{key});
     return;
   }
-
   dbg("uridnsbl: complete_a_lookup %s", $ent->{key});
-  my @answer = $pkt->answer;
   my $j = 0;
+  my @answer = $pkt->answer;
   foreach my $rr (@answer) {
     $j++;
     my $str = $rr->string;
@@ -1099,7 +1098,9 @@
     my $rr_type = $rr->type;
 
     if ($rr_type eq 'A') {
-      $rdatastr = $rr->rdatastr;
+      # Net::DNS::RR::A::address() is available since Net::DNS 0.69
+      $rdatastr = $rr->UNIVERSAL::can('address') ? $rr->address
+                                                 : $rr->rdatastr;
       if ($rdatastr =~ m/^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/) {
         $rdatanum = Mail::SpamAssassin::Util::my_inet_aton($rdatastr);
       }