Verify leads before they hit your lemlist campaign

Why lemlist campaigns punish unverified leads

lemlist is a cold-outreach sequencer: you load leads, define email and LinkedIn steps, and lemlist paces the sends across your connected mailboxes. That pacing is the whole point — it mimics human sending so mailbox providers keep trusting your domain. A single import of stale or guessed addresses undoes it. Each undeliverable address becomes a hard bounce the moment step one fires, and bounces are the fastest way to tell Google and Microsoft that your sender is careless.

lemlist reports bounces, but by then the damage is booked against your domain. Warm-up raises your reputation slowly over weeks; a batch of bounces can knock it down in an afternoon and quietly push your good replies into spam. The fix is not more warm-up — it is never letting a dead address into the campaign in the first place.

Verifly runs a real mailbox check per address and returns deliverable, undeliverable, or risky, with disposable, role, and catch-all flags. You verify the list, drop the undeliverable rows, then import only clean leads into lemlist. Your warm-up stays intact and your reply rate reflects real humans, not bounce noise.

Verify before the lemlist import, step by step

1. Assemble the lead list you plan to import — a CSV export from your finder, a scrape, or a purchased list.
2. Register a free Verifly key at verifly.email/api/v1/autonomous/register: 100 credits, no card, no captcha.
3. POST the email column to /verify/batch in chunks. lemlist imports happen per campaign, so verify per campaign too.
4. Keep only rows where result is deliverable. Decide per campaign whether risky and catch-all rows are worth the deliverability gamble.
5. Import the clean CSV into your lemlist campaign and let the sequence run against real mailboxes only.

const emails = leadCsvRows.map(r => r.email)

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()
const importable = results.filter(r => r.result === 'deliverable')
console.log(`Importing ${importable.length} leads into lemlist`)