# Find erroneous local addresses
my %already_printed;
sub report {
  my $msg = shift;

  for my $del (values %{$msg->{del}}) {

    next unless $del->{lr} eq "l";  # "l" for "local"
    next unless $del->{result} eq "failure";
    next unless $del->{report} 
      eq "Sorry,_no_mailbox_here_by_that_name._(#5.1.1)/";

    my $recipient = $del->{to};
    unless ($already_printed{$recipient}) {
      print "$recipient\n";
      $already_printed{$recipient} = 1;
    }
  }
}