Key takeaway No email is sent to the address you verify. Enrow makes sure the address is correctly written and that its domain can receive mail, then checks whether the mailbox exists, for instance by asking the company's mail server whether it would accept mail for that address. That exchange stops before any message is sent, so the person receives nothing. Some domains accept mail for every address, real or not. On these catch-all domains, Enrow adapts its method and still gives you a clear answer:
- Valid Enrow could confirm that the address can receive mail.
- Invalid Enrow could not confirm it, so we advise against emailing it.
When you type an address into Enrow's free verifier, the answer usually comes back within seconds. Here is what happens in the meantime, in plain terms. The free verifier runs the same verification as the Enrow app and the API, so the steps below apply to all three.
This is different from the "confirm your email" link a website sends you when you create an account. Nobody is asked to click anything here: Enrow checks the address from the outside.
How email verification works, step by step
While you wait, the verifier shows four short labels, one after the other. Here they are, in order, with what each one covers.
1. Checking syntax and domain
Everything starts with the address itself. Enrow removes stray spaces and makes sure the address is correctly written. If it is not, the check stops there, before any server is contacted.
Next comes the domain, the part after the @. A domain set up for email normally publishes MX records: public entries that say which servers receive its mail. When a domain has no MX records, declares that it accepts no mail, or does not exist, Enrow treats it as unable to receive email, and the address comes back invalid. Addresses on known disposable domains, which provide the temporary inboxes some people use for a one-off sign-up, are treated as unusable too.
In the free verifier, a badly written address or a domain that cannot receive email is flagged with a short message rather than a result, so you can correct it right away.
2. Contacting the mail server
To find out whether the mailbox exists, one of Enrow's checks is a short conversation with the domain's mail server. It begins like any email delivery, then stops early. The check opens a connection to the server that receives the domain's mail and names the address as the recipient. The server replies that it would accept mail for that address, that it would not, or that Enrow should come back later. Enrow reads that reply and ends the conversation, before a single line of a message has been written.
It is a little like asking a building's mail room whether they would take a letter for a given name, then leaving without handing anything over.
3. Running catch-all verification
Some domains are set up to accept mail for any address, whether the mailbox exists or not. These are called catch-all, or accept-all, domains. Their server says yes to every name, so that answer, on its own, does not prove that a particular person is behind the address.
A catch-all domain gives itself away: its server accepts even an address that cannot exist there, and checking this sends nothing either.
Once a domain is known to accept everything, Enrow stops relying on its server's yes and turns to deeper checks. You still get a clear answer, valid or invalid, never a "maybe". Catch-all verification is included in every verification at no extra cost. Thomas Lucy explains why these domains are so hard to verify in his article on catch-all emails.
4. Confirming the mailbox
Finally, Enrow brings these signals together and returns its verdict. When a mail server is slow to reply, this can take a little longer.
Valid or invalid: what your result means
Enrow gives one of two answers, and each one tells you what to do next.
| Result | What it means | Should you email it? |
|---|---|---|
| Valid | Enrow could confirm that the address can receive mail | Yes |
| Invalid | Enrow could not confirm that the address can receive mail | No, we advise against it |
Some tools add other answers, such as "risky" or "unknown", and leave the decision to you. Enrow keeps to two, so that you always know what to do with each address.
Invalid does not always mean that the mailbox does not exist. It means Enrow could not confirm it: the address is badly written or disposable, its domain does not receive email, the server refused it, or no reliable answer could be obtained. In every case, our advice is the same: it is best not to send to it.
Why might an address be impossible to confirm? Mail servers do not all behave alike. Some are slow to reply, and some are set up never to reveal whether a mailbox exists.
A valid result also comes with a few caveats:
- It describes the address at the time of the check. An address that works today can stop working when its owner leaves the company, so if a list has been sitting for a while, verify it again before your next campaign. Our article on email bounce rate explains what bounced emails cost a sender.
- It means the address can receive mail. It does not prove that someone reads it: a shared address such as contact@ can be valid with no particular person behind it. Nor does it prove that your message will land in the main inbox, which also depends on how you send and what you write.
- It makes a bounce unlikely, not impossible. A mail server's answer during a check is a strong signal, not a delivery receipt.
To check a whole list, upload it to the Email Verifier: it runs the same verification on every row. Our guide to bulk email verification explains how to prepare the file first.
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What Enrow never does
The line under the email field, "No email is sent to this address", is a commitment. Here is what it covers.
- Enrow never sends a message to the address you verify. Its conversation with the mail server ends before any message is sent, and the catch-all test works the same way.
- Enrow sends the person nothing. There is no email to open, no link to click and nothing to answer. At most, a brief technical connection takes place and closes with nothing delivered.
- The same goes for the addresses Enrow finds. When the Email Finder checks an address it has found, nobody receives an email either.
If you would like to know what is recorded when you run a check, and how long it is kept, our privacy policy explains it.
