This patch handles whitelisted recipients correctly. If the recipient was whitelisted by DSPAM,
the spam score will always be zero.

--- original/amavisd	2006-05-22 22:50:47.000000000 +0200
+++ modified/amavisd	2006-05-22 22:57:16.000000000 +0200
@@ -14801,6 +14801,11 @@
   return $self->_get_set_value("confidence", $confidence);
 }
 
+sub is_whitelisted {
+  my($self, $is_whitelisted) = @_;
+  return $self->_get_set_value("is_whitelisted", $is_whitelisted);
+}
+
 sub insert_dspam_headers {
   my($self, $insert_dspam_headers) = @_;
   return $self->_get_set_value("insert_dspam_headers", $insert_dspam_headers);
@@ -14931,6 +14936,8 @@
     $self->confidence($header_value);
   } elsif ($header_name eq "X-DSPAM-Probability") {
     $self->probability($header_value);
+  } elsif ($header_name eq "X-DSPAM-Result") {
+    $self->is_whitelisted($header_value eq "Whitelisted");
   }
   $self->add_header($header_name, $header_value);
 }
@@ -15048,11 +15055,15 @@
 # changes as soon I have a distribution of DSPAM probabilities from my servers.
 # The basic idea was to use mainly the probability but high confidence values
 # should increase the score in its original direction.
+# 
+# If the sender is whitelisted by DSPAM, the function returns 0.
 # The function below should give you a range from -10 to +20. 
-# Felix Schwarz, April 2006
+# Felix Schwarz, May 2006
 sub compute_spam_level($$$) {
   my($self, $probability, $confidence) = @_;
-  if ($confidence > 0.5) {
+  if ($self->is_whitelisted()) {
+    return 0;
+  } elsif ($confidence > 0.5) {
     return 20 * ($probability - 0.5) * (1 + $confidence - 0.5) + 5;
   } else {
     return 20 * ($probability - 0.5) + 5;