Verify cold email lists before they hurt deliverability

Why one dirty cold list poisons the good ones

Cold outreach lives or dies on sender reputation, and sender reputation is scored per sending domain and IP. When a cold list is full of stale, guessed, or abandoned addresses, the hard bounces stack up fast — and mailbox providers read a high bounce rate as a signal that you are a spammer who scraped a list without permission. Once you cross roughly 2-3% bounces on a send, providers start throttling and spam-foldering the deliverable addresses on that same campaign.

That is the trap: the invalid addresses do not just fail to arrive, they drag down inbox placement for the real prospects sitting next to them in the CSV. Verifying the list before it touches Smartlead, Instantly, or Lemlist is the difference between a campaign that lands and one that silently rots in spam.

Verifly gives every address a live SMTP check and returns deliverable / undeliverable / risky plus disposable, role, and catch-all flags. Strip the undeliverable rows entirely, and make a per-campaign call on the risky and catch-all ones based on how aggressive you can afford to be with a warm versus a fresh domain.

Clean a cold list before the first send

1. Export the list from Apollo, Clay, a scrape, or a CRM into a single email column.
2. Grab 100 free credits at verifly.email/api/v1/autonomous/register.
3. Send the whole column to POST /verify/batch in one call.
4. Drop every undeliverable row, and remove role addresses (info@, sales@) that tend to bounce or annoy on cold outreach.
5. On a fresh or recently-warmed domain, exclude catch-all / risky rows too; on an established domain you can keep them and watch the bounce rate.
6. Import only the survivors into your sequencer.

const res = await fetch('https://verifly.email/api/v1/verify/batch', {
  method: 'POST',
  headers: { 'Authorization': 'Bearer vf_your_api_key', 'Content-Type': 'application/json' },
  body: JSON.stringify({ emails }),
})
const { results } = await res.json()

// conservative filter for a fresh sending domain
const safeToSend = results.filter(r =>
  r.result === 'deliverable' && !r.role && !r.disposable && !r.catch_all
)
console.log(`Sending to ${safeToSend.length} of ${results.length}`)