Email Verification Result Statuses Explained

The five statuses at a glance

Each provider has its own words for email verification results. ZeroBounce says “catch-all”, MillionVerifier says “ok”, NeverBounce says “catchall”. Smart Email Verifier turns all of them into five statuses, so a result means the same thing whichever provider you use.

Status	What it means	What to do
Valid	The mailbox exists and accepts mail.	Send.
Invalid	The address doesn’t exist, or can’t receive mail.	Remove it.
Catch-All	The domain accepts everything, so the mailbox can’t be confirmed.	Send carefully, in a separate batch.
Risky	The address exists but could hurt your sender reputation.	Don’t send.
Unknown	The provider couldn’t get an answer this time.	Re-check later.

The results table in the Verify tab shows each address, its status badge and the provider that checked it.

Valid

The provider reached the domain’s mail server, and the server confirmed the mailbox exists. This is the only status you can send to without thinking twice.

Valid doesn’t promise the email lands in the inbox. Your content, sending domain and volume decide that. It does mean the email won’t bounce because the address is fake.

Invalid

The address will bounce. Common reasons:

• The mailbox doesn’t exist. Someone left the company, or the address was mistyped.
• The domain has no mail server, or the domain has expired.
• The format is broken, like a missing @ or a stray comma.
• It’s a disposable inbox (NeverBounce only). Temporary inboxes vanish after a few minutes, so mail to them is wasted.

Remove Invalid addresses before you send. Bounces are the fastest way to get your domain flagged. Mailbox providers start paying attention once bounces pass about 2% of a send. For more, see how to reduce your bounce rate.

Catch-All

Some companies set their mail server to accept every address on the domain, real or not. The provider can’t tell [email protected] from [email protected], because both get a “yes”.

Catch-all addresses aren’t bad, just unconfirmed. Many are real people at real companies. Our advice:

1. Keep them in a separate segment rather than mixing them into your main send.
2. Send to that segment in small batches and watch the bounce rate.
3. Get a second opinion if it matters. Re-check them with another provider. Different providers sometimes resolve different catch-alls.

Risky

The address exists, but sending to it is likely to cause trouble. You’ll mostly see this with ZeroBounce and MillionVerifier:

• Spam traps. Addresses run by blocklist operators to catch senders using old or scraped lists. One hit can get your domain listed.
• Abuse addresses. People known to mark email as spam.
• “Do not mail” addresses. ZeroBounce groups disposable inboxes, role accounts and other addresses that rarely want cold email here.

Don’t send to Risky addresses. The potential cost to your sender reputation outweighs the value of one contact.

Unknown

The provider couldn’t reach a verdict on this check. It’s a “try again later”, not a “bad address”. Common causes:

• The recipient’s mail server was slow or refused to answer. Some corporate servers deliberately stall verification requests.
• Your provider account ran out of credits, or the API key stopped working. If every result is Unknown, this is almost certainly why. Check your balance with the provider, then open Settings → Test Connection.
• A temporary error at the provider.
• A disposable inbox checked by MillionVerifier. The extension doesn’t have its own badge for these yet, so they show as Unknown.

Re-check Unknown addresses after a few hours, or with a different provider. If one is still Unknown after two tries, treat it as don’t send.

Tip: Every check counts against your daily limit, including ones that come back Unknown. On the free plan (50 a day), clean your list first so you don’t spend checks on blanks and duplicates.

How each provider maps to these statuses

If you also look at results in a provider’s own dashboard, this table shows how their labels line up with the extension’s badges.

Extension status	NeverBounce	ZeroBounce	MillionVerifier
Valid	valid	valid	ok
Invalid	invalid, disposable	invalid	invalid
Catch-All	catchall	catch-all	catch_all
Risky	—	spamtrap, abuse, do_not_mail	risky
Unknown	unknown, anything else	unknown, anything else	unknown, disposable, errors

Picking a provider? Which provider should I use? compares all three. Curious about the difference between checking the format and checking the mailbox? Read email verification vs validation.