Verify addresses before SendGrid sends them

Why verify before SendGrid, not after

SendGrid is a sending platform for both transactional mail — receipts, password resets, notifications — and marketing campaigns. It tracks bounces meticulously and maintains a suppression list: once an address hard-bounces, SendGrid stops sending to it. That protects you, but it means every bad address you feed in costs you a bounce event on your reputation before it lands on the suppression list. High bounce rates push mailbox providers to throttle or block your sending IP and domain.

The trouble with catching problems only at SendGrid is timing. By the time SendGrid suppresses an address, the bounce is already recorded against you, and for transactional mail a bounced receipt or password reset is a silent failure your user never sees. Verifying at the point of collection — the signup form, the checkout, the API that adds contacts — stops the dead address from ever entering your sending flow.

Verifly runs a live mailbox check and returns deliverable, undeliverable, or risky with disposable, role, and catch-all flags. Verify at collection to keep the database clean, and batch-verify marketing lists before a campaign so SendGrid records a low bounce rate and your suppression list only fills with genuinely dead mailboxes.

Add a verification step at collection

1. Call GET /verify from your signup or checkout handler before writing the address to your database or SendGrid.
2. Register a free key at verifly.email/api/v1/autonomous/register (100 credits, no card, no captcha).
3. Reject or flag undeliverable and disposable results at the form so they never reach SendGrid.
4. For existing marketing lists, POST them to /verify/batch before a Marketing Campaigns send and drop the bad rows.
5. Send through SendGrid against verified addresses only, keeping bounces and suppressions minimal.

async function onSignup(email) {
  const res = await fetch(
    `https://verifly.email/api/v1/verify?email=${encodeURIComponent(email)}`,
    { headers: { 'Authorization': 'Bearer vf_your_api_key' } }
  )
  const data = await res.json()
  if (data.result !== 'deliverable' || data.disposable) {
    return { ok: false, reason: 'Please use a valid, permanent email address' }
  }
  // safe to store and send via SendGrid
  return { ok: true }
}