TL;DR
- Email verification checks an address without emailing it: syntax, domain and mail server, risk lists and the mailbox itself.
- The result is a category such as deliverable, risky, undeliverable or unknown, so you know what to send and what to remove.
- Run it before any campaign and again before follow-ups, because lists decay and bounces damage sender reputation.
- Some addresses can't be proven either way (catch-all domains), so a good verifier says so instead of guessing.
The six checks
- Syntax. Does the address follow the rules for an email address (one @, valid characters, sensible length)? See address syntax rules.
- Domain and mail server. Does the domain exist and publish MX records saying where its mail goes? See what an MX record is.
- Risk lists. Is it a disposable address, a role address such as info@ or sales@, or a known trap-prone pattern? See role-based addresses.
- Mailbox check. The verifier talks to the recipient's mail server and asks whether it would accept mail for that address, then stops before any message is sent. See how to verify without sending.
- Catch-all test. Does the domain accept mail for every address, real or not? If so the mailbox check can't prove much. See catch-all emails.
- Verdict. The checks combine into one result you can act on.
What the results mean
| Result | Meaning | What to do |
|---|---|---|
| Deliverable | The server accepted the address | Send |
| Risky | Catch-all, role or disposable: might work, might not | Send with care, or leave out of cold campaigns |
| Undeliverable | No such mailbox, or the domain can't receive mail | Remove |
| Unknown | The server didn't answer clearly | Retry later |
More detail in verification statuses explained.
Why it matters
Every message sent to a dead address bounces, and mailbox providers watch bounce rates. A high rate lowers the reputation of your sending domain and IP, which sends your later mail, including mail to real customers, toward spam. Verification keeps dead addresses off the list before they can do that. Lists also decay as people change jobs and abandon mailboxes: see how fast lists decay.
When to verify
- Before the first send of any purchased, scraped, exported or old list.
- At the point of capture on signup forms (real-time API or widget), to stop typos and fake addresses.
- Before follow-up steps in long sequences. See how often to verify.
What verification can't do
It can't tell you whether a person will read or reply, whether a role address reaches the right human, or prove a catch-all mailbox exists. It also can't repair a damaged reputation or fix missing SPF, DKIM or DMARC records: check those with the authentication checker.
FAQ
Does email verification send an email?
No. A mailbox check ends before any message is sent. Mail Exchange never sends a message.
Is email verification the same as email validation?
People use the words interchangeably; some vendors reserve validation for format checks only. See the verification vs validation page.
How accurate is email verification?
It depends on the list. Catch-all domains and slow servers limit what any verifier can prove, which is why unknown and risky results exist.
Instantly
Smartlead
HubSpot
Mailchimp
Apollo
Zapier
Google Sheets
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