Verify an address
This page verifies one address at a time. For the rest there is Rooster4am, my data service:
- Email list cleaning — send a CSV of any size and get it back with every row deep-checked, invalids removed, catch-alls and role accounts flagged or stripped, and a summary you can hand to whoever asked.
- Verified B2B lead data — Apollo, Sales Navigator and Crunchbase-sourced lists built to your ICP and verified before delivery, so the first send does not burn the domains you just warmed.
How it works
Shape and domain
The address is checked against the rules mail servers actually enforce, then the domain is resolved. No MX record and no fallback A record means nothing can be delivered there, and the check stops.
Known-bad lists
The domain is compared against disposable-mail providers and the address against spam-trap and role-account patterns. These are the cheap failures — worth catching before touching the server.
Ask the mailbox
In a deep check the verifier connects to the highest-priority mail exchanger and issues RCPT TO for the address. A 250 means the mailbox exists; a 550 means it does not; a 4xx or silence means the server is not saying.
Catch-all test
A second RCPT TO for a random, impossible address at the same domain. If that one is accepted too, the domain is a catch-all and the first answer proved nothing — the result is downgraded and you are told why.
Email verification statuses explained
The verdict on top is the summary. The status underneath it is the verifier's own label, and each one implies a different action.
| Status | What the server said | Send to it? |
|---|---|---|
| safe | Mailbox exists, domain is not a catch-all, no flags raised. | Yes. |
| catch_all | The server accepts every address at the domain, so the mailbox cannot be confirmed either way. | Carefully. Small batches, watch bounces. |
| role_account | A shared or functional inbox: info@, sales@, hello@, support@, billing@ and similar. | Not for cold outreach. Many senders block these. |
| unknown | The server did not give a usable answer — greylisting, a timeout, or a provider that hides mailbox status behind a generic response. | Retry later; otherwise treat as catch-all. |
| inbox_full | Mailbox exists but is over quota and bouncing right now. | Not now. Re-check in a week. |
| invalid | Malformed, no MX, or the server explicitly rejected the recipient. | No. It will hard-bounce. |
| disabled | The provider has suspended or deactivated the account. | No. |
| disposable | A temporary inbox from a throwaway-mail service. | No. Nobody is reading it. |
| spamtrap | A known trap address planted by a blocklist operator. | Never. Remove it and audit the list. |
Why verify email addresses before a cold email campaign
Mailbox providers score a sender on what happens after the message is accepted, and a hard bounce is the loudest signal there is: the sender is mailing addresses that do not exist, which is what spammers with scraped lists do. Google and Yahoo's bulk sender rules put a hard ceiling on spam complaints; bounces have no published number, but in practice a campaign that bounces more than about 2% of its sends starts losing inbox placement within days, and the sending tools most agencies use will pause a mailbox on their own at 3–5%. On a fresh domain with no history, the tolerance is lower still.
Verification is the only lever that removes bounces before they happen. A list that has been through a deep check bounces well under 1%, which keeps every domain in the fleet in the reputation band where the warm-up work actually pays off.
Catch-all addresses: what email verification cannot tell you
A catch-all domain answers “yes, I will take that” to any local part, so a verifier cannot tell a real mailbox from a made-up one. About a third of company domains behave this way, more among small firms on Microsoft 365. The address may well be real — the person exists, the pattern matches their colleagues — but you are taking that on faith.
The workable approach is to treat catch-alls as their own segment: keep them to a minority of any send, put them in a separate sequence so a bad batch cannot drag the rest down, and watch that segment's bounce rate on the first send. If it stays under 3%, keep going. If it climbs, stop the segment and find better addresses for those accounts.
Deep check or quick check: two kinds of free email validation
The quick check validates syntax, resolves MX, and screens for disposable and role addresses in well under a second, but it never talks to the mailbox. Every address at a real domain comes back valid, including ones that do not exist. It is the right check for a sign-up form, where the goal is to stop throwaway addresses without making the user wait. It is the wrong check for an outreach list.
The deep check adds the SMTP conversation and the catch-all test. It usually takes one to three seconds; a slow or greylisting server can take longer, and the page will tell you when it is waiting.
Privacy: what happens to the address you enter
The address is sent from your browser to a small worker on this site, which forwards it to the verification engine (Reoon) that performs the SMTP checks, and returns the result. The result is cached for 24 hours under a hash of the address so a second look does not cost another server conversation; the address itself is not stored or logged by this site beyond that, and nothing is ever sent to the address.
There is a light rate limit per person to stop scripts hammering the mail servers on the other end, and a bot check runs quietly in the background — you will only ever see it if something about the session looks automated.
Bulk email verification and email list cleaning
A single-address checker is for the address in front of you: the reply you are about to send, the lead that just came in, the pattern you guessed for a prospect. It is the wrong tool for a spreadsheet. When you have a list — a few hundred rows from a conference, or two hundred thousand from a data export — the job is email list cleaning: every row through the deep check, invalid and disabled addresses removed, catch-alls and role accounts separated so you can decide what to do with them, and a report showing what came out.
That is what Rooster4am does, and it is my own service, so the standard is the one I hold my agency clients to: lists that bounce under 2% on the first send. If you need the list built as well as cleaned — Apollo, Sales Navigator or Crunchbase sourcing against your ICP, verified before delivery — that is the other half of it.
Frequently asked questions
Is this email verification tool really free?
Yes. No account, no credit card, no trial that ends. Each check costs me a little server time, so there is a per-minute limit per person and a bot check in the background, but for the way most people use it — one address at a time, now and then — you will never notice either.
How many email addresses can I verify for free?
As many as you need, one at a time, within a light rate limit that keeps scripts from draining the shared pool. If you find yourself pasting addresses in a loop, that is a list, and list cleaning at Rooster4am will be faster and give you a file back.
Does the verifier send an email to the address?
No. It opens an SMTP conversation with the domain's mail server, states a recipient, reads the server's answer and disconnects before any message is transmitted. The mailbox owner sees nothing.
Why does a Gmail or Outlook address I know is real come back as unknown?
Some providers refuse to reveal mailbox status during the handshake and answer every recipient the same way, or greylist unfamiliar connections with a temporary 4xx. The verifier reports what the server said rather than guessing. Retry later; if it stays unknown, treat the address as a catch-all.
What is a catch-all address, and is it safe to send to?
A catch-all domain accepts mail for any local part, so the server cannot confirm a specific mailbox. The address is often real, but it might not be. Send in small numbers, in a separate segment, and let the bounce rate on the first batch decide.
Why is a role account flagged? It's a real mailbox.
It is real, but it is shared. info@ and sales@ are read by whoever is on rota, replies are rare, and complaints are common because the recipient never asked to be contacted. Most cold email platforms exclude them by default, and a list heavy with them looks scraped.
What score counts as good?
The score is the verifier's confidence, out of 100, that a message will be delivered to a real person. Above 80 with a safe status is a clean address. Between 50 and 80 usually means a catch-all or a role account. Below 50 means something is wrong.
Can I upload a list or CSV here?
Not on this page — it is built for one address at a time. For a list of any size, use Rooster4am's email list cleaning: the same deep check on every row, invalids removed, catch-alls and role accounts flagged, and a clean file returned.
How accurate is it?
For non-catch-all domains, an SMTP check is close to definitive: the server either has the mailbox or it does not. The uncertainty lives in catch-all and unknown results, which is why they are reported separately rather than folded into a yes.
Is my address or my list stored?
The result is cached for 24 hours against a hash of the address so repeat checks are free, and nothing else is kept by this site. The verification engine that performs the SMTP check processes the address to answer the request.
What's the difference between this and the MX checker?
The MX checker tells you which provider hosts mail for a domain. The verifier goes one step further and asks that provider whether a particular mailbox exists. Use the MX checker to understand a domain; use the verifier to clear an address.
An address verified as safe still bounced. Why?
Mailboxes are deleted, quotas fill up, and companies migrate providers. A result is a snapshot. Re-verify anything more than a couple of months old before a campaign, and always before mailing a list you did not build recently.
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What to run next
The checks that most often follow this one.
More in this category
Guides that go deeper
When the tools tell you something is wrong
The diagnostics here are free and always will be. When the fix is bigger than a DNS record, this is the work I do.
Deliverability rescue
Mail landing in spam, replies gone quiet, or a domain suddenly blocked. I find the actual cause rather than guessing, and fix it.
- Authentication and alignment failures
- Blocklist delistings and reputation repair
- Gateway and filter-level blocks
- A written report on what broke and why
Email & sending infrastructure
Sending domains, inboxes, authentication and warmup, built to survive volume instead of burning down in a month.
- Domain and inbox fleets at any scale
- SPF, DKIM, DMARC and tracking domains
- Google Workspace — Silver Partner
- Handover documentation you actually own
Domain, DNS & migration
Changing registrar, mail provider or host without a day of downtime or a week of mail silently failing.
- Registrar and nameserver moves
- Workspace and Microsoft 365 migrations
- MX, SSL and subdomain cutover
- Staged rollout with rollback at every step
Monitoring & retainer
Infrastructure drifts. Records get edited, certificates expire, domains get listed. Ongoing eyes on the fleet.
- Scheduled checks across every domain
- Alerts before your clients notice
- Monthly reporting
- Priority response when something breaks
Start with a call
Bring a domain and the symptom. I will tell you what is actually wrong and whether you need me at all — plenty of people leave that call able to fix it themselves.
Thirty minutes, no pitch
We will run the checks together on your actual domains, and you will leave knowing what is broken, what it takes to fix, and what it should cost. If that is a job you can do in-house, I will say so.