If you have never bought email verification before, the same questions come up. Some are technical, some are commercial, some are about whether this is even legal. Here are honest answers to the 20 we get most often.
How does email verification work?
The verifier opens an SMTP connection to the receiving mail server, runs through the start of a delivery handshake (HELO, MAIL FROM, RCPT TO), reads the server's response, then disconnects. If the server responds positively, the address exists. If negatively, it does not.
Is it accurate?
For most addresses, yes - 98%+ accuracy in controlled tests. For catch-all domains (about 15 to 30% of business domains), SMTP cannot give a definitive answer because the server accepts everything. Good verifiers flag catch-all as a separate status.
Does the recipient see anything?
No. The verifier never sends the DATA stage of the SMTP conversation. No message is delivered. The recipient never knows the check happened. The only entity that sees the verification is the receiving mail server, and what it sees is identical to any other server checking deliverability.
Is it legal?
Yes. SMTP verification is a standard protocol behavior performed millions of times per second across the internet. It is not regulated under GDPR, CAN-SPAM, or any other framework. You do need to handle the email addresses you process under applicable data protection law, but the verification act itself is not restricted.
Will I get banned for verifying?
No. The mail server you are checking does not know who is checking. Verifiers route through rotating IPs to stay within reasonable per-domain rate limits, but mailbox providers do not retaliate against verifiers as a category.
How much does it cost?
Pay-as-you-go from $0.004 per credit. Bundle pricing drops to $0.0008 at higher volumes. Credits never expire with MailoClean.
Do unknown results cost credits?
No. If we cannot reach the server or it returns ambiguous responses, you do not pay. Only definitive results are billed.
How fast is verification?
Median 1.4 seconds per single check. Bulk lists run at thousands of addresses per minute through parallel workers.
Can I verify in bulk?
Yes. Up to 1 million addresses per upload. We process in the background and notify you when done.
Are credits shared between bulk, single, and API?
For MailoClean, yes. One wallet, three modes of access.
What if my list is gigantic?
Bulk handles up to 1 million per upload. For larger jobs, contact enterprise sales for batched processing.
Do I need an API key for the homepage verifier?
No. Five free checks per day from the homepage, no signup required. For larger volumes, create an account.
How long are results cached?
24 hours. Verifying the same address twice within 24h costs zero credits the second time.
What about international addresses?
Fully supported. Latin and non-Latin domain names, IDN, regional ISPs, country-code TLDs all work.
What does each status mean?
- Valid: mailbox exists and is deliverable.
- Invalid: mailbox does not exist.
- Risky: deliverable but uncertain quality signals.
- Catch-all: domain accepts all addresses; specific mailbox status unknown.
- Disposable: temporary throwaway email.
- Role-based: shared mailbox like info@ or admin@.
- Spam trap: known spam-trap address; do not send.
- Unknown: verifier could not reach a definitive answer.
Should I send to catch-all addresses?
Carefully. Many catch-all addresses are real; some are not. Use name-plausibility filtering and lower send frequency.
How do I integrate verification with my stack?
Three ways: bulk upload via CSV, real-time API call, or no-code workflow tools (Zapier, n8n, Make).
What if MailoClean is down?
99.9%+ uptime since launch. For application code, build a 5-second timeout and accept the signup with a "needs reverify" flag if the API fails. Background reverify within the hour.
Is my data shared or sold?
No. Read the privacy policy for the full details.
Can I get a DPA for GDPR compliance?
Yes. Contact support to sign one.
Start verifying
Free single check on the homepage, API docs, or bulk upload. All three use the same engine.