This patch adds the new configuration variable "$dspam_mail_size_limit" (defaulting to undef)
which is roughly equivalent to "$sa_mail_body_size_limit" but applies only to SpamControl::DSPAM.

Mails which are bigger than $dspam_mail_size_limit bytes will not be scanned by SpamControl::DSPAM.

--- original/amavisd	2006-05-22 22:59:45.000000000 +0200
+++ modified/amavisd	2006-05-22 23:20:49.000000000 +0200
@@ -201,6 +201,7 @@
       $mailfrom_to_quarantine $warn_offsite $bypass_decode_parts @decoders
       @av_scanners @av_scanners_backup $first_infected_stops_scan
       $sa_spam_report_header $sa_spam_level_char $sa_mail_body_size_limit
+      $dspam_mail_size_limit
       $undecipherable_subject_tag $localpart_is_case_sensitive
       $recipient_delimiter $replace_existing_extension
       $hdr_encoding $bdy_encoding $hdr_encoding_qb
@@ -15081,17 +15082,30 @@
   $self->prepare_header_edits() if $self->insert_dspam_headers();
 }
 
+sub mail_too_big($) {
+  my($self) = @_;
+  my($size_limit) = c('dspam_mail_size_limit');
+  if (defined $size_limit and $self->msginfo()->msg_size > $size_limit) {
+    do_log(1, "DSPAM: not wasting time on DSPAM, message bigger than %s bytes: %s", 
+            $size_limit, $self->msginfo()->msg_size);
+    return 1;
+  }
+  return 0;
+}
+
 sub check {
   my($self,$msginfo) = @_;
-  do_log(5, "DSPAM check called!");
   $self->prepareSpamcheck($msginfo);
+  if ($self->mail_too_big()) {
+    return undef;
+  }
   $self->start_dspam();
   $self->read_dspam_output();
   if ($self->error_occurred) {
     return undef;
   }
   my($spam_level) = $self->compute_spam_level($self->probability, $self->confidence);
-  do_log(1, "spam check resulted in p=".sprintf("%1.3f", $self->probability).", confidence=".sprintf("%1.3f", $self->confidence)." => spam level=".sprintf("%1.1f", $spam_level));
+  do_log(1, "DSPAM: spam check resulted in p=".sprintf("%1.3f", $self->probability).", confidence=".sprintf("%1.3f", $self->confidence)." => spam level=".sprintf("%1.1f", $spam_level));
   $msginfo->spam_level($spam_level);
   $msginfo->spam_status("DSPAM");
   return $spam_level;