Free Email Bounce Checker

See whether an email will bounce before you hit send — protect your sender reputation.

Why check for bounces first

Every hard bounce chips away at your sender reputation and pushes future mail toward spam folders. Checking an address against live DNS and the receiving mail server before you send removes most avoidable bounces — invalid syntax, dead domains and missing mailboxes.

Invalid addresses

Malformed addresses are caught before they ever reach a send.

Dead domains

Domains with no mail server (no MX) are guaranteed hard bounces.

Missing mailboxes

Where the server allows it, we confirm the mailbox actually exists.

Disposable

Temporary addresses churn fast and bounce soon after signup.

Catch-all

Catch-all domains accept everything, so treat them as higher risk.

Role addresses

Shared inboxes like info@ often have low engagement and complaint risk.

Check bounces from your code

Scrub whole lists before a send: pass your CatchThis API key as a bearer token to skip the CAPTCHA. Every response includes a willBounce verdict (no, likely, yes or unknown) backed by a real SMTP probe.

curl "https://catchthis.email/api/check?email=name@example.com" \ -H "Authorization: Bearer ct_your_api_key" # → { "willBounce": "yes", "status": "undeliverable", # "smtp": { "checked": true, "deliverable": false, "code": 550 }, # "mx": { "found": true, ... }, "score": 15 }

Loop it over your list and drop everything where willBounce is yes (and review likely). Usage is tracked per key on your dashboard. Rate-limited for fair use.

Just validating one address?

For a straight yes/no on a single address, the free email checkerruns the same checks with a validation-first summary.

Frequently asked questions

What is an email bounce checker?

It predicts whether a message to an address will bounce, before you send it. We validate the syntax, resolve the domain's MX records live, probe the mailbox over SMTP where possible, and flag disposable, role and catch-all addresses that raise bounce risk.

Why do emails bounce?

Hard bounces come from invalid addresses, dead domains with no mail server, or mailboxes that no longer exist. Soft bounces come from full mailboxes or temporary server issues. Checking before you send removes most hard bounces.

Is the bounce checker free?

Yes — no signup, no card. Paste an address and see its bounce risk instantly.

Can I lower my bounce rate with this?

Yes. Removing addresses flagged undeliverable or risky before a campaign keeps your bounce rate down and protects your sender reputation.

Why can't every mailbox be confirmed?

Many mail servers block automated SMTP verification to stop abuse, and catch-all domains accept every address. When a mailbox can't be confirmed we mark the bounce risk as unconfirmed rather than guess.