03Bulk Verification
Bulk email verifier — clean a list of up to 100 addresses in one call
A list built over months — signups, a CSV export, a scraped lead list — accumulates typos, dead mailboxes and disposable addresses. Checking it one address at a time doesn't scale; checking it with a single list-wide score hides which addresses actually failed and why.
Endpoint behavior below matches RankFabrik's Verify API documentation, checked 14 September 2026.
How the batch endpoint works
Step 1
Deduplicated on receipt
Send a CSV or a comma-separated list of up to 100 addresses. Duplicates are collapsed before any check runs — you're never billed twice for the same mailbox in one call.
Step 2
Checked in parallel
Each address runs the same syntax → MX → SMTP pipeline as the single-address endpoint, independently, so one slow mail server doesn't hold up the rest of the batch.
Step 3
Summarized by verdict
The response carries a per-verdict count alongside the full per-address results — how many valid, how many risky, how many invalid — without hiding which specific addresses landed where.
GET /verifier-lot?emails=a@…,b@…,c@…
{
"recus": 3,
"count": 3,
"summary": { "valid": 2, "risky": 1 },
"results": [
{ "email": "a@…", "verdict": "valid", "code": "mailbox_exists" }
],
"truncated": false
}An unsettled address isn't billed
On a batch, only addresses actually settled count toward billing. If a time budget runs out before
every address gets a verdict, the response says so with truncated: true — and the
addresses that didn't get checked cost nothing. No paying for a mailbox the probe never reached.
Get access
The batch endpoint is part of the Verify API, in early access. For a quick manual spot-check first, the free single-address tool uses the same pipeline.
Questions
How can I verify if an email address exists?
Run it through syntax, MX-record and SMTP-probe checks, in that order. On a list, the same three checks run per address, deduplicated first so the same mailbox isn't billed twice, then rolled up into a summary count per verdict.
Is there a free email verification tool?
For a handful of addresses, yes — https://rankfabrik.com/email-checker checks one address at a time at no cost. For a list of dozens or a hundred, the batch endpoint below is built for the job.
Is there a free API that can verify addresses?
The batch endpoint, <code>/verifier-lot</code>, is part of the Verify API, in early access at https://rankfabrik.com/produits/verification.
How to verify the legitimacy of an email address?
On a list, legitimacy is a per-address question that still needs a per-address answer — a single list-wide score hides which specific addresses are disposable, catch-all, or dead. RankFabrik's batch summary breaks the list down by verdict, and each address keeps its own reason.