Recheck one group.
Unknown or mailbox full can be run again without redoing the addresses that already have a result.
✳ CHECK THE LIST BEFORE YOU SEND.
Check the list
you already
have.
Upload the file you were about to send. Fewer bad addresses go out with the campaign.
Free is 100 credits, enough to see one list. The usual first purchase is 5,000 credits for $15. Unknown is free.
01 WHAT YOU ARE PAYING FORA finished answer.
A finished answer.
Nothing else.
- You pay only when the answer is finished. Deliverable, undeliverable, catch-all, disposable, role account, and mailbox full cost one credit. Unknown, greylist, a blocked check, an unreachable mail server, and a system error cost nothing, and the hold is released.
- Catch-all is not marked deliverable. A domain that accepts every address is its own result. Putting those in a send is how lists bounce. Same for role accounts (info@, support@) and disposable inboxes: they are separated so the customer can leave them out.
- Unknown is not invalid. People delete unknown rows and then blame the tool.
- A running list can take more addresses. New rows join that same run. They do not need a second list, and they do not need to wait until it finishes.
- Stop, and unused credits come back. Finished results stay billed. Holds on checks that never finished are released. Duplicates inside one file are stored once and are not billed twice.
Three ways in, one set of credits.
The portal, an API key, or an agent in Cursor, Claude, or ChatGPT. Webhooks if they want the result pushed to their own URL. MCP server · Webhooks
A real invoice.
Secuno LLC, Sheridan, Wyoming, downloadable from Billing after Stripe confirms payment.
The $15 pack.
5,000 credits is the usual first purchase. Free is 100 credits so you can see one list before you pay. See pricing · Check a list free
02 SMALL DETAILS. BIG DIFFERENCE.Thorough where it matters.
Get to know the results ↗Thorough where it matters.
Simple where it should be.
01 / THE FOUNDATIONSGood emails start
Good emails start
with the basics.
Catch malformed addresses. Check domains and mail routes. Stop obvious failures before they reach your next campaign.
Syntax validationDNS & MX lookup
alex@example.com↗
01Syntax check✓
02Domain lookup✓
03Mail server found✓
ILLUSTRATIVE CHECK SEQUENCEMAIL SERVER RESPONSE
02 / THE MAILBOX250 Recipient acceptedAsk the server.
Understand the answer.
SMTP checks read the receiving server’s response without delivering a message. Temporary failures stay separate from invalid addresses.
SMTP checks ↗Spot the signals.
Keep your judgment.
Catch-all is not marked deliverable. Role accounts and disposable inboxes stay separate so you can leave them out.
Risk detection ↗A MORE HUMAN WAY TO HANDLE DATA.Unknown.
Unknown.
Not unwanted.
A quiet mail server shouldn’t cost
you a real customer.
WHEN THE SERVER NEEDS MORE TIME
retry_later→Give it another check.
Some servers delay, block, or decline verification requests. We distinguish inconclusive responses from definitive failures—so you know when to retry instead of reject.
Clarity over guesswork ↗A verification result reflects the signals available at check time. It doesn’t guarantee inbox placement or future delivery.
03 LESS WORK BETWEEN YOU AND YOUR NEXT SEND.Bring your list.
Bring your list.
Leave with clarity.
No maze of settings. Just a straightforward path from contact data to a more informed decision.
01↓
Bring it in.
Upload a CSV or TXT file, or paste the addresses you already have. A running list can take more. New rows join that same run.
.CSV.TXT{ API }
02⌁
Let the signals speak.
Follow verification progress and review the actual result behind each address.
CHECKING THE DETAILS
03↗
Make your next move.
Separate likely reachable contacts, risky addresses, and results that need another check.
✓ Ready to review
05 EVERY RESULT HAS A REASON.Less “what now?”
Less “what now?”
More “got it.”
The label is just the beginning. Here’s what it means—and what to do next.
01Deliverable1 credit+
Deliverable means the server accepted the recipient. It does not mean the message will reach the inbox.
02Invalid / undeliverableCorrect or remove+
The address has a format problem or a definitive domain or mailbox failure. Correct the address or exclude it from your active sending list.
03Catch-all / disposable / roleReview the risk+
These signals mean different things: catch-all domains do not confirm an individual mailbox; disposable addresses may be short-lived; role accounts are shared. Apply a separate policy to each.
04Unknown / retry laterRecheck, don’t guess+
Unknown is not invalid. The server did not give a clear yes or no. Leave the row, or recheck that group later.
BEFORE YOU UPLOADThree rules the
Three rules the
file has to keep.
Catch-all is not deliverable.
A domain that accepts every address is its own result. Leave it out of the send unless you wrote a rule for it.
Check a list free ↗Unknown is not deleted.
No clear answer is not invalid. Leave the row, or recheck that group later.
Check a list free ↗Add rows to a running list.
New addresses join the same run. You do not need a second list, and you do not need to wait until it finishes.
Check a list free ↗THE DETAILS, SIMPLIFIEDGood questions.
Good questions.
Clear answers.
What is email verification?+
Email verification checks the structure, domain, and available mail-server signals of an address. It helps identify invalid and potentially risky contacts before you send.
Does checking an address send an email?+
The verification engine checks DNS and SMTP responses without delivering an email message to the recipient.
Is catch-all marked deliverable?+
No. A domain that accepts every address is its own result. Putting those in a send is how lists bounce.
Can I add more emails while a list is still running?+
Yes. New rows join that same run. You do not need a second list, and you do not need to wait until it finishes.
Will verification guarantee inbox delivery?+
No. Inbox placement also depends on sender reputation, authentication, content, recipient behavior, and provider policies. Verification is one part of responsible sending.
Why can an email return an unknown result?+
Some providers block probes or return ambiguous responses. Timeouts and temporary restrictions can also prevent a conclusive check. These results should not be treated as definitive invalid addresses.
Understand the details.
Make the next move.
All guides ↗FIELD GUIDE
What Does Email Verification Actually Check?
Understand the main email verification checks and their limits, including address syntax, mail records, mailbox responses, and risk flags.
Read more ↗FIELD GUIDEHow to Clean an Email List Without Losing Context
A practical workflow for preparing a CSV list, reviewing verification results, and preserving useful source information.
Read more ↗FIELD GUIDECatch-All Email Addresses: What the Result Means
Learn why a catch-all domain can make mailbox verification inconclusive and how to review the result without false certainty.
Read more ↗THE FILE YOU WERE ABOUT TO SEND.
Upload the file
you were about to send.
Free is 100 credits. Unknown stays free.
You pay only when the answer is finished.