Know which contacts to remove, review, or include before your next campaign.
Upload a list or check one address. Each result includes a status, a plain-language reason, and a recommended action — so you can export a file you are willing to send. Live demo below; no signup required.
Bulk CSV & Excel verificationPricing from €35 for 10,000
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No signup. Real SMTP probe. 3 of 3 free verifications left.
From list to send decision
Built for outbound teams and agencies preparing contact lists before a campaign. The goal is a clear next step per address — not a mysterious score you have to interpret alone.
- Step 1
Add the contacts
Check one address, paste a list, or upload a CSV, TXT, Excel or PDF file. Duplicate rows are removed before checking.
- Step 2
See what to do with each row
Remove Invalid addresses. Review Risky ones (for example catch-alls). Include Valid rows using the recommended action. Retry Unknowns — those credits come back automatically.
- Step 3
Export a campaign-ready file
Download everything or only the outcomes you choose, as CSV or Excel, with your original columns kept next to the result and action.
- Step 4
How the check works
After syntax, domain and MX checks, we talk to the receiving mail server up to the recipient step — no email is sent. A made-up address on the same domain shows whether the domain accepts everything (catch-all).
Trying one address first? Check an email address · Cleaning a whole file? See how bulk verification works · How SMTP verification works
What each result means — and what to do with it
Every address gets one of four statuses, a reason and a recommended action. The recommended action is the send decision, and the reason explains it: “the server said this mailbox does not exist” and “this domain accepts any address” call for different decisions.
Valid
Positive evidence for this address: either the mailbox was confirmed, or the receiving server accepted it while rejecting a made-up address on the same domain. Confirmed scores 100; accepted-with-control checks score 88 and are still not proof a person exists.
What to do: Safe to send — that is the recommended action for both confirmed and accepted-with-control Valid rows. It is not an inbox-placement guarantee.
Risky
There is a reason for caution. For example, a catch-all domain accepts any address, so acceptance alone does not confirm this mailbox. Providers that accept without confirming, mailboxes that are full right now, and policy signals such as toxic domains or possible spam traps also land here.
What to do: Send with caution, Review before sending or Try again — each row states which, and why. A catch-all domain's acceptance on its own is never treated as mailbox confirmation.
Invalid
A reason not to send — for example the server said the mailbox does not exist, the domain has no working mail route, or the domain is disposable. A disposable domain is a policy classification, not proof that the address cannot receive mail.
What to do: Do not send. Remove the address, or fix it when a likely typo correction is suggested.
Unknownshown as “No reliable result” in the dashboard
No reliable answer: the server timed out, deferred or blocked the check. It says nothing about whether the address is good or bad.
What to do: Follow the row's action: try again later, or review it before sending when the server blocked the check. If a charged check finishes as Unknown, that credit is refunded automatically.
A check talks to the receiving mail server without sending a message. Acceptance at that stage does not guarantee inbox placement — spam filtering happens later, when you actually send. Scores rank results; they are not delivery probabilities. Results also age, so re-check a list that has been sitting for months.
More detail: Valid vs Invalid vs Risky vs Unknown · What is a catch-all domain? · Try the email checker
Why teams choose 
Practical differences in the send decision, the export, and the bill — not a claim that we are universally more accurate than every verifier.
Reasons you can act on
Every row explains what happened — for example a rejected mailbox versus a blocked verification attempt — so you are not left guessing from a bare label.
Recommended actions
Safe to send, send with caution, review, retry, or do not send — the same wording your Campaign export uses, so filtering a list matches what you see on screen.
Unknown credits returned
When a charged check finishes Unknown, that credit returns to your balance automatically. We do not invent Valid when the probe could not establish an answer.
Catch-alls stay Risky
If a domain accepts arbitrary addresses, acceptance alone does not confirm a mailbox. Those rows stay Risky with the catch-all evidence shown — never painted Valid to inflate the list.
Export what you will send
Download by outcome or recommended action. Campaign exports keep your original columns beside the result; Full exports add the technical evidence when you need it.
Live bulk progress
Watch each job fill in live, and download finished rows before the whole file is done.
Native cold-email connectors
Instantly, Smartlead, and Lemlist are listed as Production connectors: connect with an API key, sync leads, verify, and push status. Optional auto-sync can be enabled on a connected list (implemented and covered by tests; not claimed here as a live ops proof). HubSpot is currently hidden from the gallery; several other CRMs are Beta. Not the same as CSV import into another tool.
Configurable retention
Results stay in your workspace by default. If you opt in, finished results and uploaded addresses are deleted automatically after the window you set (1 hour to 90 days; 24 hours if you do not change it). Billing records remain; backups and logs are not part of that deletion.
HTTP API for scripts and products
Create an nxv_ key in the dashboard, then verify single or bulk. Optional wait=true returns a completed single result in one request when the job finishes in time.
Ready to experience the difference? See it in action
When Nexiphor is a good fit
Choose us when you prepare outreach lists and need a reason and recommended action on every row — especially catch-alls kept out of Valid, and Unknown credits returned. MillionVerifier competes hard on bulk USD price and a large ESP catalogue; ZeroBounce sells a wider deliverability suite. Prices below are different pack sizes and currencies — not like-for-like.
Unknown results
- NexiphorVerifier
- Credit returned automatically
- MillionVerifier
- Marketed as a refund for risky emails; terms describe discretionary goodwill credits
- ZeroBounce
- Not charged
Published pay-as-you-go price
- NexiphorVerifier
- €35 for 10,000 (EUR)
- MillionVerifier
- $89 for 50,000 (USD)
- ZeroBounce
- $39 for 2,000 (USD)
| What you pay for | NexiphorVerifier | MillionVerifier | ZeroBounce |
|---|---|---|---|
| Unknown results | Credit returned automatically | Marketed as a refund for risky emails; terms describe discretionary goodwill credits | Not charged |
| Published pay-as-you-go price | €35 for 10,000 (EUR) | $89 for 50,000 (USD) | $39 for 2,000 (USD) |
Checked on 30 October 2026 against ZeroBounce's pricing page and MillionVerifier's homepage (help centre and terms last reviewed 15–16 Oct 2026). Prices: our smallest pack, ZeroBounce's stated minimum purchase, and the 50,000 example on MillionVerifier's homepage — each in its own currency. Try the free demo or 100 signup credits yourself. Vendor terms change — check them before you decide.
Full comparisons: NexiphorVerifier vs ZeroBounce · NexiphorVerifier vs MillionVerifier
Pay for the addresses you actually check
One credit per address. Buy a pack when you need one — there is no subscription, and unused credits stay on your balance.
Credit packs
One credit, one address checked
Packs are one-off purchases in EUR. If a check ends Unknown, the credit goes back to your balance.
- Single address checks
- CSV, Excel or pasted lists
- A reason on every result
- Unknown results refunded
- Credits don't expire
- Catch-alls stay Risky
Choose a pack size
10,000 credits
See every pack and what uses a credit€0.0035 per address
Buy credits100 free credits on signup. Unknown results return to your balance automatically.
Privacy you can read
Retention, subprocessors, and security limits are described in plain language — including what automatic deletion does and does not cover.
Configurable retention
Off unless you turn it on; until then, results stay in your workspace. When enabled, finished results and uploaded addresses are deleted automatically after the retention window you set (1 hour to 90 days; 24 hours if you do not change it). Billing records and job totals are kept. This is not immediate deletion, and it does not erase backups, server logs, or shared domain caches. (Settings still label the control “zero-storage” for compatibility.)
Published privacy documents
A privacy policy and data processing agreement are published. They describe what we have implemented. They are not a certification.
TLS for the site and probes
The website and API use HTTPS. Mailbox probes use TLS when the receiving server accepts it.
No list resale
We do not sell your lists or use them to train public AI models. Verification does send addresses to recipient mail servers, and sometimes to Microsoft's directory.
Start with 100 free credits No card required
Verify a sample in the browser, upload a campaign list when you are ready, and buy credits only when you need more volume.