Solution to block unwanted donors my automatically triggering the spam catcher. Using the spam catcher means that clients don't see the attack donations.

donation_block_by_email_addresses.html

<meta name="special" content="badguy@thieves.bizi,fraudster@fraud.bizi,jingle@bells.bizi.uk">
<script type="text/javascript">
  document.addEventListener('DOMContentLoaded', function () {
    if (document.querySelector('input[name=donate_page_KEY]') != null) {
      document.querySelector('.salsa form').addEventListener('submit', function () {
        var e = document.querySelector('input[name="Email"]');
        var m = document.querySelector('*[name="special"]');
        if (e != null && m != null) {
          var list = (m.getAttribute('content') || '').split(',').map(function (x) { return x.trim(); });
          if (list.indexOf(e.value.trim()) != -1) {
            document.querySelector('input[name^="first_name"]').value = m.name;
          }
        }
        return true;
      });
    }
  });
</script>