New Playbook: Cold Email Infrastructure Setup Guide

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Free bulk email verifier: paste up to 5, verify each in seconds

Paste up to 5 business emails, one per line. Each one runs through a real SMTP handshake and comes back with a verdict: deliverable, undeliverable, catch-all, or risky. Export the deliverable ones as a CSV when you are done. No signup, no API key.

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0/5 emails

mark_email_read Paste up to 5 emails above to verify them all at once.

What is bulk email verification?

Bulk email verification is the same SMTP check as single-email verification, run across a list. The verifier opens a connection to each recipient's mail server, asks if the address exists, and reads the answer without actually delivering a message. With a list, the same logic loops one address at a time so you get a verdict for every email in the batch.

The difference between single and bulk is workflow. Single is for a one-off check before you reply to a prospect. Bulk is for cleaning a list before you launch a campaign. This widget sits in the middle: small batches of up to 5, useful for testing pattern guesses or sanity-checking a handful of leads from LinkedIn.

For full lists of hundreds or thousands of addresses, you want a paid verifier with parallel processing, retry logic for soft fails, and a downloadable cleaned file. Mailsfinder's paid plans handle that. This free tool is for quick checks, not full list hygiene.

Why bulk verification matters before a cold campaign

Inbox providers (Gmail, Outlook, Yahoo) watch bounce rate as one of the strongest signals of a spammer. Cross the 2% bounce threshold and your sending domain gets throttled, then quarantined, then blacklisted. One unverified bulk send can knock a domain out of the inbox for 30 days or more, even after you stop sending.

2%

Bounce rate ceiling Gmail and Outlook tolerate before throttling your domain.

30+ days

Recovery window from one bad list send. You sit in spam folders the entire time.

99%

Verified deliverability rate on Mailsfinder addresses, after SMTP cleaning.

How this verifier works

dns

MX records

Confirms each domain has mail servers configured. No MX means no email is possible, the address is marked undeliverable immediately.

handshake

SMTP handshake

Connects to each mail server and asks if the mailbox exists. The conversation stops before any message is delivered, so nothing counts as a real send.

filter_drama

Catch-all detection

Flags domains that accept every address. Catch-alls return OK regardless of whether the mailbox exists, so they get a risky verdict not a green one.

block

Disposable and role-based

Flags throwaway domains (mailinator, tempmail) and group addresses (info@, sales@) so you do not waste sends on inboxes nobody reads.

Limits and when to upgrade

The free tool gives 5 verifications per IP per day, enough to sanity check a handful of leads. Sign up free for 100 per day, no card required. Paid plans start at $9.99 per month for 300,000 credits, designed for teams running cold outreach at volume.

Free (this page)

$0

5 verifications per IP per day. No signup.

Signup (free)

$0

100 verified lookups per day, forever. No card.

Monthly

$9.99/mo

300,000 credits per cycle. Bulk CSV upload, parallel processing.

Lifetime

$249 once

2,000,000 credits, lifetime pool. Pay once, verify forever.

When to upgrade

Verifying more than 100 emails per day, cleaning CSV lists, or running an outreach campaign. Sign up free and decide later.

Frequently asked questions

Why only 5 emails at a time? expand_more
Each SMTP check opens a real TCP connection to the recipient's mail server. That costs compute and IP reputation on our side. Capping the free tool at 5 keeps it fast for everyone and prevents abuse. If you need 100 per day, sign up at app.mailsfinder.com. If you need bulk CSV upload, the paid plans start at $9.99 per month.
Does this hurt my sender reputation? expand_more
No. The SMTP handshake never actually sends a message. It opens a connection, asks if the mailbox exists, reads the answer, and closes. Nothing arrives in the recipient's inbox, no bounce is recorded against your sending domain, and the check uses our IP pool not yours.
What does "catch-all" mean? expand_more
A catch-all domain accepts every address sent to it, even ones that do not exist. The SMTP server returns "OK" regardless. Mail to a non-existent address either bounces later or is silently dropped. Catch-alls are flagged "risky" here so you can decide whether to send. For paid plans, our system runs additional checks to distinguish real mailboxes inside catch-all domains.
Can I export the results? expand_more
Yes. After verification finishes, click "Export CSV" to download a file with email, verdict, deliverability, safe-to-send flag, catch-all flag, role-based flag, MX host, and reason for every address you checked. You can also click "Copy deliverable" to grab just the green ones to your clipboard for pasting into your outreach tool.
How does this compare to ZeroBounce or Hunter? expand_more
ZeroBounce and Hunter both verify via SMTP, same as Mailsfinder. The difference is volume and price. ZeroBounce charges $0.008 per verification at small volume. Hunter charges around $0.005. Mailsfinder's $9.99 per month plan works out to roughly $0.00003 per credit, two orders of magnitude cheaper at volume. For one-off checks of 5 emails, the free tool on this page is enough.

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Verify thousands, not just 5

Sign up free for 100 daily credits, or upload a CSV and verify thousands in one go. No card required.

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