How to Check Whether an Email Address Actually Exists (Without Sending an Email)
Validate an email address without sending an email? With this real-time API you avoid errors, spam, bounces, and frustration.
A customer types [email protected] into your registration form. You send a confirmation email. It never arrives. The customer is gone. This scenario is entirely preventable — without sending a single email.
What Do We Mean by "Actually Exists"?
A valid email address has the correct syntax ([email protected]). But that does not guarantee the address can actually receive mail. An address can be syntactically correct but:
- The domain no longer exists
- The mailbox does not (or no longer) exist
- It is a disposable address
- It is a role address such as
info@ornoreply@
The ApiCheck email validation checks all of this — without sending an email.
Why Traditional Validation Falls Short
A required email HTML attribute or a simple regex only checks the format. That does not flag [email protected] as an error, because syntactically it is correct.
How Our Email Validation Works
The validation takes place in three steps:
Step 1: Syntax Check
The format is checked: Is there an @? Is the domain format correct? Are there invalid characters?
Step 2: Domain Check
We check whether the domain exists and whether there are active MX records (mail exchange records). Without MX records, the domain cannot receive email.
Step 3: SMTP Mailbox Check
We send an RCPT TO: command to the mail server and check whether it responds with 250 OK. This simulates the start of an email delivery without actually sending an email. Response 250? Mailbox exists. Response 550? Mailbox does not exist.
What Does Our API Return?
{
"valid": true,
"reason": "ok",
"disposable": false,
"role_account": false,
"free_provider": true
}
| Field | Description |
|---|---|
valid |
Is the address reachable? |
reason |
Reason for rejection (invalid_syntax, domain_not_found, mailbox_not_found, etc.) |
disposable |
Is it a disposable address? |
role_account |
Is it a role address (info@, noreply@)? |
free_provider |
Free provider such as Gmail or Hotmail? |
What Does This Solve?
- Typos:
@gnail.com,@yaho.nl,@hotmail.conare caught - Fake accounts: Disposable addresses are recognized
- Bounces: Emails to non-existent mailboxes disappear into the void
- Reputation damage: Too many bounces damages your domain reputation with mail servers
Customers who use the email validation see up to 80% fewer invalid email addresses in their database.
Integrations & Usage
The API works for any system that can make HTTP requests:
- WooCommerce (via plugin)
- WordPress Contact Form 7 (via plugin)
- Custom PHP, Node.js, Laravel applications
- CRM systems via direct API connection
Frequently Asked Questions
Will the customer receive anything from the check? No. The check is completely invisible to the end user.
Is the SMTP check GDPR-compliant? Yes. We do not store email addresses and do not send any emails. The check is purely technical.
What if a mail server blocks the SMTP check?
Some large providers (such as Google) block SMTP checks. In that case we return valid: true with reason: unverifiable — so you still have the choice.
Conclusion
With the ApiCheck email validation API, you filter out incorrect, fake, and unreachable email addresses at the point of entry — without sending a single email. That not only saves you bounce problems, but also reputation damage and dirty customer data.