Verify an Email List Before a Campaign

To verify an email list before a go-to-market campaign, run one Cargo batch call over the addresses with a verifier such as waterfall.verifyEmail (0.1 credits per address), then send only to the addresses that come back valid. Verification is billed per check: unlike a finder, a verifier charges for every address it checks, whatever the verdict.

No ZeroBounce, NeverBounce or Bouncer account is needed: Cargo calls each verifier on its own key and bills credits. The steps below are the verify-email-list skill, end to end.

What 2.09M verification runs show #

Cargo platform data, 90 days to Oct 16 2026: 2.09M email verification runs across 603 workspaces, and 66.4% of them came back valid.

The other third came back with some other verdict: invalid, catch-all, unknown, or a provider-specific status. That is the share of a typical list a verifier will not vouch for, and the reason to verify before the send rather than after the bounces.

What the verdicts mean #

• Valid. The receiving server confirmed the mailbox exists. Send.
• Invalid. The domain or the mailbox does not exist. Drop it: these are the hard bounces that hurt a sending domain.
• Catch-all (accept-all). The domain’s server accepts mail for any address, real or not, so no verifier can tell whether this particular mailbox exists. A catch-all result is not a pass and not a fail; it is the absence of an answer. Many company domains are configured this way, and no provider resolves it by checking harder.
• Unknown. The server did not give a usable answer during the check (it timed out, greylisted the request, or refused it). Re-verify later or treat it like catch-all.

What to do with catch-all addresses is a sending decision, not a verification result. The conservative choice is to leave them out of a cold campaign. The other choice is to send to them from a small, separate batch and watch the bounce rate before sending more.

Run it #

1. Install and sign in

npm install -g @cargo-ai/cli
cargo-ai login --email you@company.com                 # sends a code
cargo-ai login --email you@company.com --code 123456   # creates the account on first use

There is no browser step, so a coding agent can run this itself. A new account starts with 100 free credits and no card, which covers 1,000 checks on waterfall.verifyEmail or zeroBounce.verifyEmail.

2. Pilot on 10 addresses

cargo-ai orchestration action execute-batch \
  --action '{"kind":"connector","integrationSlug":"waterfall","actionSlug":"verifyEmail"}' \
  --records '[{"email":"ada@example.com"},{"email":"grace@example.org"}]' \
  --limit 10 --wait-until-finished

--limit 10 submits only the first ten records, so you can read the verdicts and the cost before the full run. Every record is {"email":"..."}, on every verifier except Findymail, which also takes "objectType":"email".

3. Run the list and download the verdicts

Drop --limit to run every address, then:

cargo-ai orchestration batch download --uuid <batch-uuid>

The result is a CSV: your input columns, plus the verifier’s fields prefixed cargo_, for example cargo_email_status on waterfall.verifyEmail.

4. Split the list

Keep the valid rows, drop the invalid ones, and set catch-all and unknown aside for the decision above. Do not re-verify the whole list with a second provider: every check is billed again.

Verifiers and the field to read #

Prices are each action’s list price. In the run log, Cargo marks a check as passed only when the verifier said valid: status or result equal to valid, valid or verified true. Two verifiers bill differently from the rest:

• bouncer.verifyEmail returns no data, and charges nothing, when Bouncer says undeliverable. Every other verdict comes back with its data and is charged, so read status and domain.acceptAll rather than assuming a returned row is deliverable.
• icypeas.verifyEmail reports probable, undeliverable and not_found certainties as not valid, and returns no data when Icypeas has no result.

Verify even when the finder sent a status #

A finder grading its own result is not an independent check. If the addresses came from an email finder, run them through a verifier before the send; find and verify work emails at scale covers both steps as one flow, and the find-work-email skill covers the finding.

Frequently asked questions #