Bulk Email Verifier for CSV and Excel Lists

What a bulk email verifier does

A bulk email verifier checks many addresses in one job, so you don't have to look them up one at a time. Run bulk email verification before a send, and you see which addresses will bounce and can leave them out. That matters because bounces harm your sender reputation.

It doesn't send email for you, and it isn't a guide to list hygiene. For inactive subscribers, sign-up sources and the rest of the routine, read our guide on how to clean your email list.

Three ways to run a bulk email verifier

CampaignKit is web-based bulk email verifier software, so there's nothing to install. Pick the route that fits how your list reaches you:

• The web app. Paste addresses or upload a file in the browser, then download the results. The steps are below.
• The API. Bulk email verification from your own code: the Validation Jobs API takes a file upload, reports the job status and returns the results for download. Webhooks can announce when a job has finished, so you don't need to keep asking. Everything else is on the developers page.
• Integrations. Verify contacts in the tools you already use: Zapier, n8n, Mailchimp, HubSpot, Mailjet, FluentCRM and Claude.

Verify a file in the web app

This online bulk email verifier tool runs in your browser:

1. Sign up for CampaignKit. No credit card is needed.
2. Open a new validation and add your addresses. Paste them into the form, or upload a TXT or CSV file or an XLS or XLSX spreadsheet. Each file can be up to 20 MB.
3. Let the job run. When it's done, the job summary shows how your list splits across Deliverable, Undeliverable and Risky.
4. Download what you need. Choose one or more groups and save them as a CSV, ready to import into your email platform.

In a file, put the addresses in the first column or under a column headed "email". In an Excel file, CampaignKit reads the first sheet.

What the results mean

Each address ends up in one of three groups, named as you see them in the app:

Group	Meaning	Next step
Deliverable	Safe to send to	Keep it on your list
Undeliverable	Will bounce	Take it off your list
Risky	May cause issues	Review it, or send to it as its own segment

The download dialog starts with only Deliverable selected. Catch-all addresses count as Deliverable and are included unless you clear "Include catch-all addresses". A catch-all domain accepts mail for any address, so a single mailbox can't be confirmed and some of these addresses may still bounce. Our post on catch-all emails and whether to send to them helps you decide.

Treat Deliverable as a strong signal, not a promise of delivery: besides catch-all domains, some mail servers won't confirm whether an address exists.

What else to expect in the download:

• Your columns stay put. If your file had a header row, your original columns keep their order and the result columns follow after them.
• Typo suggestions. When an address looks like a misspelling of a well-known email provider's domain, the file suggests the corrected address. Confirm it with the contact before you change anything.
• 30 days to download. Validation jobs are deleted 30 days after they're created, so save your CSV in time.

Bulk email verifier pricing

You start with 200 free validations and no credit card. That's a one-time allowance for testing a sample or a short list, not a free plan that renews. After that you buy credits in packs: there's no subscription, and credits never expire.

Pack size	Price	Cost per 1,000 emails
2,500 emails	$6	$2.40
10,000 emails	$15	$1.50
50,000 emails	$75	$1.50
100,000 emails	$120	$1.20

See all packs and a price comparison dated September 2026 on the pricing page. Verifying more than 100,000 emails? Contact sales for custom pricing.

One address or a whole list?

• One address, no account: use the single-address checker.
• A list or a file: you're on the right page.
• Sign-ups in your own app: validate them through the API, see developers.
• Getting a list ready for a send, start to finish: see email list cleaning.

More about bulk verification

• How to clean your email list, step by step.
• The best email verification tools, compared.
• How to reduce bounce rates.
• The Validation Jobs API reference and the webhooks reference.
• Run CampaignKit on your own servers with the self-hosted edition.
• How we handle your data: security and the data processing agreement.