Email Verification FAQ & Support

What is email verification?

Email verification checks whether an email address is real, correctly formatted and able to receive mail — without sending an actual message. It combines syntax, domain, MX and SMTP checks into a confidence score.

Does verifying an email send them a message?

No. MailTester performs a safe SMTP probe that never delivers an email to the recipient, so verification is invisible to them.

How accurate is MailTester?

For most domains MailTester is highly accurate. Some providers (like catch-all domains) intentionally accept all addresses, so those are flagged as 'risky' rather than guessed.

What is a catch-all domain?

A catch-all (or accept-all) domain accepts email for any address at that domain, so it's impossible to confirm a specific mailbox exists. MailTester marks these as risky.

What is a disposable email address?

A disposable or temporary email address is designed to expire after a short time. MailTester detects thousands of disposable domains so you can filter them out.

What's the difference between a hard and soft bounce?

A hard bounce is a permanent failure (the address doesn't exist). A soft bounce is temporary (mailbox full, server down). Verification helps you avoid hard bounces before you send.

How often should I clean my email list?

At minimum every 3–6 months, and always before a large campaign or when importing a new list. Re-verify addresses that have been inactive for a long time.

Is there a free daily quota?

Yes — you get a set number of free email verifications and finds every day with no signup required. Beyond that, paid plans include monthly credits and you can top up your balance any time, paying only for what you use.

How is my data handled?

MailTester is DPDP/GDPR-friendly. Administrators can choose to hash, encrypt or not store verified addresses, and you can export or delete your data at any time.

Can I verify a whole CSV file?

Yes. Upload a CSV for bulk verification in your dashboard, or send addresses through the bulk API endpoint.

Why does an email show as 'unknown'?

Some mail servers deliberately hide whether a mailbox exists (greylisting or catch-all). When we can't confirm either way, we return 'unknown' rather than guessing.