diff -Nur qpsmtpd-0.84/plugins/spamassassin qpsmtpd-0.84_size_limit/plugins/spamassassin
--- qpsmtpd-0.84/plugins/spamassassin	2010-02-13 06:30:12.000000000 +0100
+++ qpsmtpd-0.84_size_limit/plugins/spamassassin	2013-04-10 19:27:06.541888148 +0200
@@ -112,7 +112,8 @@
   my ($self, $transaction) = @_;
 
   $self->log(LOGDEBUG, "check_spam");
-  return (DECLINED) if $transaction->data_size > 500_000;
+  my $limit = (defined $self->{_args}->{size_limit}) ? $self->{_args}->{size_limit} : 500_000;
+  return (DECLINED) if $transaction->data_size > $limit;
 
   my $remote  = 'localhost';
   my $port    = 783;