Email Verifier

An email verifier (email checker) is a piece of software that checks if a given email address exists, and if it can receive an email you send. Email verifiers run email addresses through multiple tests to accurately assess their validity and existence, and show you a result for each verified email address.

Using an email verifier is important before contacting email addresses you didn't email before, or when it's been a while since you last reached out. This is because wherever you find email addresses, including your own database, they can be:

• Fake,
• Old and obsolete,
• Mistyped,
• Personal as opposed to professional.

Below is a description of all email checks performed by the Email Verifier on every email address:

• Valid format: First, we validate the format of the email address is correct and looks something like email@provider.com.
• Gibberish email address: We check to ensure the address doesn't look like a fake email address. For example, 1e49cs1pb6@company.com doesn't pass the test in most cases.
• Disposable email address: We check if the email address has a domain name used for temporary email addresses.
• Webmail email address: We verify if the email address uses a webmail service like Gmail or Yahoo.
• Presence of MX records: We check if there are MX records on the domain. If there aren't, the email address can't receive any emails.
• Presence of SMTP server: This check is successful if we are able to connect to the SMTP server (indicated in MX records).
• SMTP check: We test the email address and see if its server is willing to accept emails for the address (without sending an email.)
• Accept-all domain: We check if the server has an accept-all (catch-all) policy that accepts all the email addresses.
• Accept-all verification: We're able to verify accept-all addresses with several major email providers using a proprietary solution.

We wrote an article explaining how email verification works.

Hunter returns one of five statuses, and you're only charged for three of them.

• Valid: the mailbox is active and can receive email, so it's safe to use.
• Invalid: it failed the checks and doesn't exist, so don't send to it.
• Accept-all: the domain is set up to accept mail for every address on it, including ones that were never created, so neither Hunter nor most other tools can fully confirm deliverability.
• Disposable: a temporary address that self-destructs. Free.
• Unknown (sometimes shown as Blocked): the server greylisted or blocked the check, so we couldn't determine validity. Free. If a server is simply slow, Hunter keeps checking in the background rather than returning Unknown straight away.

A verification costs 0.5 credits on the All-in-One Outreach plans and 1 verification credit on Data Platform plans. Verifying the same address again in the same month is free, though bulk uploads are always charged.

Not with full certainty, and nor can any other tool. An accept-all (catch-all) domain is configured to accept mail for every address on it, including ones that were never created, so an SMTP check returns OK whatever you ask it. Hunter marks these as accept-all rather than guessing, and filters out made-up name-variant addresses so what's left is more likely to be a real mailbox.

Expect accept-all addresses to bounce at around half your list's invalid rate: if 10% of your list is invalid, roughly 5% of the accept-all addresses may bounce. Our guide to accept-all addresses has the experiment behind that number.

A valid result means the address passed every check Hunter runs and is safe to use, but verification is never 100% certain: it reflects the mailbox at the moment it was checked. A small percentage of valid addresses still bounce, because mailboxes get deleted, fill up or start rejecting mail afterwards and bounces can come from deliverability problems on your own sending domain too, not just from the address. That's why it's worth verifying shortly before you reach out. If you see bounces on addresses you verified the same day, that's unusual: send them to contact@hunter.io with the bounce messages and support will look into it. The pitfalls of email verification covers the cases where every verifier struggles.

No, Hunter's email verification service doesn't rely on sending actual emails to the addresses being verified. Instead, we connect to the recipient's SMTP server to verify the address, and we use our knowledge about the given email domain.

If you recently verified an email address with Hunter's Email Verifier and it was verified as 'valid', then it's safe to use—provided your email server is configured well and your sender reputation is satisfactory. We usually observe a bounce rate lower than 1% for these email addresses. However, email verification can never prevent all emails from bouncing, because the existence and validity of the recipient address is not the only factor.

Yes, our email checker is free. The Free plan lets you verify up to 100 email addresses per month (0.5 credits each). If you need more email verifications, review our pricing.

Credits are shared across the Email Finder and Domain Search, where a search costs 1 credit, so how far they go depends on what else you use them for.

Yes, you can verify a list of email addresses with the Bulk Email Verifier, whether they are work addresses or personal ones. Hunter will run the same email verifications on your entire email list.

Because a model will invent an email address that looks correct. Asked for someone's contact details, it predicts the most likely pattern, firstname.lastname@company.com, and returns it with the same confidence as a real one. The address is plausible, it is not real, and you find out when it bounces.

We measured it. Across 1,604 model-generated addresses that got a conclusive verdict, 76% were invalid and only 14% verified as valid. The strongest model tested returned a valid address about 20% of the time, and famous companies fared no better than unknown startups: 71% invalid either way. Connect the same model to Hunter and that rises to 78%.

A verifier is the check between the model's guess and your send: it either confirms the mailbox exists or says it cannot, so the agent has a fact to act on rather than a guess. Hunter returns a status for every address, and says when it cannot verify one instead of guessing.

Verify right before you send. In an 8-week experiment on 1,278 addresses that started out valid, 2.3% had gone invalid and another 3.2% had turned accept-all by the end, so 5.5% of a carefully cleaned list was no longer safe to contact. More than 2% was already invalid after four weeks, and 2% is the bounce rate at which a cold campaign is worth pausing to troubleshoot. Contact data decays on its own as people change jobs and companies reconfigure domains to accept-all, so a list that was clean when you built it will not stay clean. On a paid plan Hunter re-verifies your contacts automatically every month, and email verification best practices covers how to fit it into a routine.

Yes, we offer a free API to all Hunter users. It provides the most flexible way of verifying email addresses. High-volume users can use our Data Platform plans to only pay for email verification, without access to other parts of the platform.

You can integrate Hunter's Email Verifier into your CRM. We have built native integrations with leading platforms like HubSpot or Pipedrive, and we can serve nearly every other platform through Zapier automations. For more, browse our Integrations or read how to integrate email verification with your CRM.

An email verifier can help you spot fake subscribers and submissions before they reach your database, either as a scheduled clean-up or as a real-time check inside the form. That protects your organization from two common attacks:

• Making you unintentionally email non-existent mailboxes to cause bounces and blocklisting
• Making you pay more for your email marketing tool by inflating your subscriber count

Contacting an address you didn't verify risks a bounce, and every bounce chips away at the sender reputation that decides whether the rest of your email reaches the inbox. Two things go wrong:

• Your email can bounce. Every bounced message harms your sender reputation and prevents other emails you send from landing in the recipient's primary inbox.
• Your message may not reach the intended recipient without you ever knowing, because you don't always receive the bounce-back message.

Email validation checks whether an email address is correctly formatted and appears to follow the syntax rules of email addresses (for example, name@domain.com and not namedomain@.com). It ensures there are no typos, extra spaces, or invalid characters. However, it doesn't confirm that the address actually exists.

Email verification goes a step further. It checks whether the email address is deliverable, that is, whether it can receive messages. A verifier typically connects to the mail server and simulates sending an email to confirm that the mailbox is active.

In short: validation ensures the email looks correct; verification ensures it exists. Our guide compares email validation and verification side by side.

There is none. “Email verifier” and “email checker” refer to the same tool providing the same service, one that confirms whether an email address is valid and deliverable. You will also see it called an email validator, an email tester, an email address checker or an email address verifier. They all describe the same job, though strictly an email validator checks the format rather than the mailbox.

A good verifier (or checker) doesn't just spot typos; it identifies invalid, risky, and accept-all addresses, helping you maintain a low bounce rate and stronger sender reputation.

In short: the two names describe one tool, so judge it on what it catches rather than what it is called.

Yes. The Email Verifier checks whether an address is valid and deliverable. To find out who is behind it, use the Reverse Email Lookup tool, which returns the person's name, job title, company, and social profiles from an email address.