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Privacy-focused email bounce checker
BlockSurvey's free email bounce checker is a privacy focused tool. It helps you to find if an email is valid or not! Simply enter email addresses and click the "Verify" button and Email Bounce Checker will check the email for each address.
We don't like email bounces. You don't like email bounces. So we've built the best privacy-focused bounce checker out there, so we can keep our open rates high and your response rate even higher. Our privacy-friendly email checker uses open source libraries to determine if an email bounced. Emails are not logged, not tracked. If you need to store or compare an address later without keeping it in the clear, turn it into a one-way hash and keep only the digest. It's open source and you can host it as well
Know how the privacy-focused email bounce checker works
01
Step 1 : Regex and Typos
Blitzkrieg, thats the pace of the world around us, a few pattern and typo errors may occur, so we begin our checks here.
02
Step 2 : Disposable
Our second check is for those using burner emails, disposable emails, etc.
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Step 3 : MX and SMTP
Finally, we get a tad more technical and perform the traditional Server checks.
What we do — and don't — with what you submit
A real inbox check needs a real connection to the destination mail server, so we're upfront about where that step runs and what happens to your list afterwards.
01
Fast checks run first
Regex syntax, common typos, and disposable-domain matching happen before anything else, so addresses with an obvious pattern error or a burner domain are flagged without needing the slower MX/SMTP step at all.
02
MX and SMTP checks run on our server, by necessity
A browser tab cannot open a raw SMTP socket to a mail server, that's a restriction of the browser itself, not a design choice. So when regex and typo checks pass, the addresses are sent to a BlockSurvey server to look up MX records and, if the SMTP checkbox is on, simulate sending a mail. That's the only way to find out if a mailbox is actually reachable.
03
Nothing logged, nothing stored
The addresses you enter are used only to run that one verification request. They are not logged, not stored, and not tied to an account, there isn't one. Close or refresh the tab and the results are gone; nothing sits in a database afterwards.
The tool itself is also open source on GitLab, so you don't have to take our word for how the checks run.
Built for anyone cleaning up a list
Checking a handful of addresses before they go anywhere shouldn't require an account or a credit card.
01
Marketers & growth teams
Catch typos and dead addresses in a segment before a campaign goes out, so a send doesn't take a hit to open rates or sender reputation over a handful of bad rows.
02
Developers
Spot-check a signup or checkout flow for disposable domains and malformed addresses while you're still building the form, instead of finding out from a bounce report later.
03
Anyone who doesn't want to upload a list to a marketing SaaS
A free, no-account check for a short list, without handing it to a platform that keeps it. If the list itself needs to travel further, encrypt it in your browser before you send it to anyone.
Want to create secure online forms and surveys?
BlockSurvey runs on zero-knowledge surveys, so responses are encrypted on the respondent's device and the server stores nothing readable.
More free privacy tools
Explore more →
These tools run in your browser and keep what you enter on your device. When you need to collect answers from other people the same way, use privacy-first survey software.
Frequently Asked Questions
- An email bounce is an automated message from an mail server that informs the sender that their email has not been delivered to its intended destination. This will indicate that something has gone wrong either on the sender side or the recipients’ side.