A bulk email verifier that protects your sender reputation
Validate via syntax, MX records, and SMTP.
The Kavex email verifier checks every address on your list before it ever reaches a campaign, so a single bad import does not drag down your deliverability. It runs syntax, domain and live mailbox checks and hands each address back with a clear status, valid, invalid, risky or catch-all. Clean the list once, send with confidence, and stop guessing why your open rates are slipping. You pay per address checked, with no subscription tier to climb.
A RUN OF 1,000 EMAILS ON THIS SOURCE, AT 1 PER EMAIL
Four columns on every row.
These come with the run and cost nothing extra. Add-ons widen the same sheet, and you pay only for the ones you switched on.
| Status | Reason | Catch-all | |
|---|---|---|---|
| anna@northstudio.nl | valid | mailbox accepts mail | no |
| sales@brightlabs.co | catch-all | domain accepts all mail | yes |
| j.doe@varzcae.de | invalid | domain has no MX record | no |
| info@pixelforge.io | valid | mailbox accepts mail | no |
| old.user@studiomeraki.fr | risky | mailbox full | no |
Say what you want. Read the price first.
Everything else is a ceiling or a filter. The estimate moves with the numbers you type, so the run never surprises you at the end.
The email verifier runs each address through several layers of checks. First it validates the syntax and rejects malformed addresses. Then it confirms the domain actually exists and publishes MX records, which catches typo domains and dead companies. Finally it opens a real SMTP conversation with the receiving mail server to confirm the specific mailbox will accept mail.
Every address comes back with a plain status and a reason. Valid means the mailbox accepted the check. Invalid means it was rejected outright. Catch-all means the server accepts everything and cannot confirm a single mailbox, and risky flags full mailboxes or temporary failures. You decide how strict to be from there.
It is built for bulk work. Drop in a CSV exported from another tool, a signup list or a scrape, and the email verifier processes the whole file and returns it annotated, so you can suppress the dead weight before it touches your sending reputation.
The email verifier confirms a mailbox by speaking SMTP directly to the receiving server, the same protocol mail itself uses. It looks up the domain MX records, connects to the mail exchanger and runs the recipient check without ever delivering a message, the inbox owner sees nothing.
This VPS has port 25 open, so the email verifier runs these checks natively instead of paying a third-party API per address. Catch-all domains are detected by probing an address that cannot exist; if the server still says yes, every result on that domain is labelled catch-all so you can treat it with the caution it deserves.
Charged per delivered row. If the source holds fewer than you asked for, the rest of the credits go back to your balance the second the run ends.
One thousand emails, itemised.
One line, because this source has nothing bundled on top. You pay the rate times the rows the run actually delivered.
| Line | Rate | Units | Credits |
|---|---|---|---|
| Email Verifier | 1 / email | 1,000 emails | 1,000 |
| 1,000 emails | 1 / email | 1,000 credits | $1.00 |
$0.001 PER FINISHED EMAIL · ONLY DELIVERED ROWS ARE BILLED
What people point it at.
Four ways this source is used today. Every one of them is the same run, the same export and the same credit pool.
- Demand-gen teams cleaning a CSV before importing it into Mailgun, SendGrid or an outreach platform.
- Founders running pre-launch hygiene on a large waiting list so the first send does not bounce.
- SDRs vetting a list built in another tool before loading it into a sequence.
- Product teams validating signup emails to cut fake accounts and undeliverable onboarding mail.
The rest of the web, contact & ai stack.
Same credit pool, same export. Chain the output of one run into the next without paying for the list twice.
Asked before the first run.
Short answers, no accordion to click through. If something is still missing, the help pages go deeper.
What do the result statuses mean?
Valid means the mailbox accepted the check, invalid means it was rejected, catch-all means the domain accepts all mail and cannot be pinned to one mailbox, and risky covers full mailboxes or temporary failures. Each row also carries a short reason.
What is a catch-all address?
A catch-all domain accepts mail to any address, so the server cannot confirm whether one specific mailbox exists. The email verifier flags these separately so you can send to them knowingly rather than assuming they are all valid.
How fast is a large list?
Verification runs as a batch job and processes addresses continuously. A few thousand addresses typically complete in minutes, and the finished file is ready to download as soon as the job ends.
How do results export?
Your list downloads as a CSV with the original address plus status, reason and catch-all columns added. Filter it in any spreadsheet to keep only the addresses you want to send to.