How to verify an email address
There are four reliable ways to confirm an email address exists — from a manual MX lookup to an automated SMTP check. Use the verifier below for an instant answer, then read the methods to understand what it is doing.
5 of 5 free checks left today — no signup required.
Method 1 — Check the syntax and the domain
Start with the obvious failures: a missing @, an invalid TLD, or a domain with no MX record. Run 'nslookup -type=mx domain.com' — if nothing comes back, the domain cannot receive mail at all and every address on it is invalid.
Method 2 — Run an SMTP mailbox test
Connect to the domain's mail server on port 25, issue HELO, MAIL FROM and then RCPT TO with the address you are testing. A 250 response means the mailbox is accepted; 550 means it does not exist. Disconnect before DATA and nothing is delivered. Most ISPs block outbound port 25, which is why a hosted verifier is used in practice.
Method 3 — Handle catch-all domains correctly
Probe the domain with a random address that cannot exist. If the server accepts it, the domain is catch-all and no mailbox-level answer is trustworthy. Segment those addresses separately rather than deleting or trusting them.
Method 4 — Verify the whole list automatically
For anything beyond a handful of addresses, upload a CSV and let the engine run all checks in parallel with retries, greylisting handling and per-provider rate limits. You get a clean send file, a suppression list and your original columns preserved.
What not to do
Do not send a test email to check an address — a bounce damages your sender reputation and a silent accept teaches you nothing on a catch-all domain. Do not rely on regex alone, and do not trust a verifier that never returns 'unknown'; honest engines admit when a server refuses to answer.
Frequently asked questions
How do I verify an email address without sending an email?
Resolve the domain's MX records and open an SMTP session with the mail server, issuing RCPT TO for the address and disconnecting before the message body. The server tells you whether the mailbox is accepted and nothing is delivered.
Can I verify an email address for free?
Yes. The verifier on this page runs 5 free checks per day with no account.
How do I verify a Gmail address?
Gmail answers mailbox-level SMTP queries, so a standard verification returns a definitive valid or invalid result for @gmail.com addresses.
How do I verify thousands of addresses?
Upload a CSV of up to 50,000 rows in the dashboard or call the bulk API endpoint; results come back with per-row status, reason and score.
Verify your whole list
Paste up to 10 addresses in the bulk checker, or create a free account to upload a CSV and use the API.