Verify emails in Google Sheets with one formula

const RW_URL = 'https://api.askravn.com/v1/tools/';

function rwCall_(tool, payload) {
  const key = PropertiesService.getScriptProperties().getProperty('RAVN_API_KEY');
  if (!key) throw new Error('Add RAVN_API_KEY under Project Settings > Script Properties');
  const res = UrlFetchApp.fetch(RW_URL + tool, {
    method: 'post',
    contentType: 'application/json',
    headers: { Authorization: 'Bearer ' + key },
    payload: JSON.stringify(payload),
    muteHttpExceptions: true,
  });
  const body = JSON.parse(res.getContentText());
  if (res.getResponseCode() !== 200) {
    throw new Error('Ravn ' + res.getResponseCode() + ': ' + body.error.code + ' - ' + body.error.message);
  }
  return body;
}

/**
 * Verifies a column of emails in one batch call.
 * Returns [status, risk_score] for each row.
 * @param {A2:A200} range The cells holding email addresses.
 * @customfunction
 */
function RW_VERIFY(range) {
  const cells = Array.isArray(range) ? range : [[range]];
  const rows = cells.map(function (r) { return String(r[0] || '').trim().toLowerCase(); });
  const unique = rows.filter(function (e, i) { return e.indexOf('@') > 0 && rows.indexOf(e) === i; });
  if (unique.length === 0) return rows.map(function () { return ['', '']; });
  if (unique.length > 1000) throw new Error('Up to 1,000 unique addresses per formula. Split the range.');

  const body = rwCall_('validate_emails', { emails: unique });
  const byEmail = {};
  (body.results || []).forEach(function (v) { byEmail[v.email] = v; });
  return rows.map(function (e) {
    const v = byEmail[e];
    return v ? [v.status, v.risk_score] : ['', ''];
  });
}