blocked by Gmail/Outlook). 5. Catch-All Detection: Identifies servers that accept all addresses.

const dns = require('dns/promises');

async function validateEmail(email) {
  const [, domain] = email.split('@');
  const result = { mxRecords: 0, hasSpf: false, hasDmarc: false,
                    smtpValid: null, isCatchAll: null, deliverability: 'unknown' };

  // 1. MX records — does the domain accept mail?
  try {
    const mx = await dns.resolveMx(domain);
    result.mxRecords = mx.length;
  } catch { result.mxRecords = 0; }

  if (result.mxRecords === 0) {
    result.deliverability = 'low';
    return result;
  }

  // 2-3. SPF + DMARC TXT lookups
  try {
    const txt = await dns.resolveTxt(domain);
    result.hasSpf = txt.some(arr => arr.join('').toLowerCase().startsWith('v=spf1'));
  } catch {}
  try {
    const dmarcTxt = await dns.resolveTxt(`_dmarc.${domain}`);
    result.hasDmarc = dmarcTxt.some(arr => arr.join('').toLowerCase().startsWith('v=dmarc1'));
  } catch {}

  // 4. SMTP RCPT TO probe (optional, often blocked by Gmail/Outlook)
  // ... skipped for brevity, see full code

  // 5. Roll up to grade
  if (result.mxRecords > 0 && result.hasSpf && result.hasDmarc) {
    result.deliverability = 'high';
  } else if (result.mxRecords > 0) {
    result.deliverability = 'medium';
  }

  return result;
}

Performance: Per-domain DNS probing takes ~50ms. For 100 emails, total validation time is ~5 seconds. Domain caching reduces costs across batches.

2. Multilingual Contact-Page Crawl

The scraper expands the URL frontier to include localized paths. This is critical for EU markets where legal requirements dictate contact page locations.

const CONTACT_PATHS = [
  // English
  '/contact', '/contact-us', '/about', '/about-us',

  // Hungarian
  '/kapcsolat', '/elerhetoseg',

  // German (Impressum is legally required)
  '/kontakt', '/impressum', '/ansprechpartner',

  // Spanish
  '/contacto', '/contactar', '/contactenos',

  // Italian
  '/contatti', '/contattaci',

  // French
  '/contactez-nous', '/nous-contacter',

  // Polish
  '/kontakt-z-nami', '/kontakty',

  // Czech / Slovak
  '/kontakt', '/kontaktujte-nas',

  // Portuguese (BR + PT)
  '/contato', '/contatos', '/contacto',

  // Dutch
  '/over-ons',
];

async function crawlForEmails(baseUrl) {
  const emails = new Set();
  const re = /\b[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,}\b/gi;
  for (const path of CONTACT_PATHS) {
    try {
      const html = await fetch(new URL(path, baseUrl)).then(r => r.text());
      (html.match(re) || []).forEach(e => emails.add(e.toLowerCase()));
    } catch {}
  }
  return [...emails];
}

3. Delta Mode & Cost Optimization

To prevent duplicate processing and billing, the scraper implements a delta mode that skips known placeId and cid values before any billable events fire.

// Skip-before-bill check
if (knownPlaceIds.has(item.placeId) || knownCids.has(item.cid)) {
  continue; // no enrich, no email validation, no billing event
}

Architecture Decisions:

• Pay-Per-Result Billing: Switched to $0.005 per delivered lead to ensure predictable costs. Failed runs cost $0.
• Preflight Budget Check: Estimates runtime before execution. If estimated time exceeds timeout, the run is refused to prevent partial results and wasted resources.

Pitfall Guide

1. Catch-All Servers: Domains may accept all RCPT TO commands but bounce messages silently. Always implement catch-all detection to avoid false positives.
2. Localization Blindspots: Assuming /contact exists in non-English markets leads to missed data. Use a comprehensive list of localized paths (e.g., /impressum for Germany, /kapcsolat for Hungary).
3. SPF/DMARC Neglect: Sending to domains without SPF or DMARC records increases spam risk. Include these checks in your validation pipeline to protect sender reputation.
4. SMTP Probe Blocking: Major providers like Gmail and Outlook often block SMTP probes. Rely on DNS-based validation (MX/SPF/DMARC) as the primary method, with SMTP as optional.
5. Duplicate Processing Costs: Without delta mode, recurring scrapes may reprocess and re-bill known leads. Implement placeId/cid deduplication to skip billable events for existing data.
6. Runtime Timeouts: Large datasets can exceed actor timeouts. Use a preflight budget check to estimate runtime and adjust configuration before execution.
7. Cost Blowout with External Validators: Using third-party services adds $0.004-$0.010 per lead. Inline validation reduces costs significantly while maintaining quality.

Deliverables

Blueprint: Inline Validation & Multilingual Crawl Architecture

• 5-Layer Validation Pipeline: MX → SPF → DMARC → SMTP → Catch-All.
• Multilingual Path List: 20+ localized contact paths covering major EU and global markets.
• Delta Mode: Skip-before-bill logic for recurring scrapes.
• Preflight Check: Runtime estimation to prevent timeouts.

Checklist: Implementation Guide

• Implement DNS-based validation (MX, SPF, DMARC).
• Add catch-all detection logic.
• Integrate multilingual contact paths (CONTACT_PATHS).
• Enable delta mode with placeId/cid deduplication.
• Configure pay-per-result billing model.
• Add preflight budget check for runtime estimation.
• Cache DNS results by domain to reduce latency.

Configuration Templates

• Validation Thresholds:
  • high: MX > 0 AND SPF AND DMARC.
  • medium: MX > 0.
  • low: MX = 0.
• Contact Paths Array: Use the CONTACT_PATHS list provided in the Core Solution.
• Billing Config: $0.005 per delivered lead + $0.00005 per run start.

Actor Link: Google Maps Email Extractor with Built-in Email Validation

• Free tier includes ~100 leads for testing.
• Source code patterns are MIT-licensed for reuse.