qpsmtpd/plugins/check_spamhelo

#!perl -w
=head1 NAME

check_spamhelo - Check a HELO message delivered from a connecting host.

=head1 DESCRIPTION

Check a HELO message delivered from a connecting host.  Reject any
that appear in the badhelo config -- e.g. yahoo.com and aol.com, which
neither the real Yahoo or the real AOL use, but which spammers use
rather a lot.

=head1 CONFIGURATION

Add domains or hostnames to the F<badhelo> configuration file; one
per line.

=cut

sub hook_helo {
  my ($self, $transaction, $host) = @_;
  ($host = lc $host) or return DECLINED;
  
  for my $bad ($self->qp->config('badhelo')) {
    if ($host eq lc $bad) {
      $self->log(LOGDEBUG, "Denying HELO from host claiming to be $bad");
      return (DENY_DISCONNECT, "Sorry, I don't believe that you are $host.");
    }
  }
  return DECLINED;
}

# also support EHLO
*hook_ehlo = \&hook_helo;