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Domain Whitelist

What it does: Checks the attendee list against a defined set of approved domains and only passes events that include at least one attendee from those domains.

Use case: Only sync meetings that involve people from your own organization or approved partner organizations, filtering out external or unknown contacts automatically.

function gate(event: GateEvent): GateResult {
  const allowedDomains = ['company.com', 'partner.org', 'contractor.io'];

  const hasApprovedAttendee = event.attendees.some((attendee) =>
    allowedDomains.some((domain) => attendee.email.endsWith(`@${domain}`))
  );

  if (!hasApprovedAttendee) {
    return { pass: false, reason: 'No attendees from approved domains' };
  }

  return { pass: true };
}

How It Works​

Unlike the simpler hasAttendee() helper, this recipe uses event.attendees.some() to iterate directly over the attendees array and check each email against a list of allowed domains. String.endsWith() ensures the match is at the domain boundary (e.g. @company.com matches alice@company.com but not alias-company.com). If no attendee matches any allowed domain, the event is blocked.

Customization​

Switch to a blocklist (block events with any attendee from a disallowed domain):

function gate(event: GateEvent): GateResult {
  const blockedDomains = ['competitor.com', 'spam.org'];

  const hasBlockedAttendee = event.attendees.some((attendee) =>
    blockedDomains.some((domain) => attendee.email.endsWith(`@${domain}`))
  );

  if (hasBlockedAttendee) {
    return { pass: false, reason: 'Event includes an attendee from a blocked domain' };
  }

  return { pass: true };
}

Separate internal from contractor events:

function gate(event: GateEvent): GateResult {
  const internalDomains = ['company.com'];
  const contractorDomains = ['contractor.io', 'agency.co'];

  const hasInternal = event.attendees.some((a) =>
    internalDomains.some((d) => a.email.endsWith(`@${d}`))
  );

  const hasContractor = event.attendees.some((a) =>
    contractorDomains.some((d) => a.email.endsWith(`@${d}`))
  );

  if (hasInternal && hasContractor) {
    return { pass: true, transform: { title: `[External] ${event.title}` } };
  }

  return { pass: true };
}