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Introduction to the MailboxValidator API

mbv_editor
Updated on July 30, 2026

4 min read

Introduction-to-MailboxValidator-API

Overview #

The MailboxValidator Single Validation API is an easy to use RESTful API that allows users to programmatically validate a single email address. This is useful for programmers who want to have email validation functionalities in their own programs or websites.

If you are unfamiliar with the term RESTful, you should read up on REST below:
https://en.wikipedia.org/wiki/Representational_state_transfer

Pre-requisite #

To use the API, you will need to sign up for an API key. If you haven’t done so, just go to the API plans page and sign up for the free API plan.

Basic usage #

GET https://api.mailboxvalidator.com/v1/validation/single?email=test@test.com&key=<your API key>&format=<json or xml>

There are basically 2 parameters when doing a GET call to the API. The email parameter is the email address that you wish to validate while the key parameter is the API key that you should have signed up for in the pre-requisite section above.

You may have noticed that there is a third parameter format. This parameter is optional and has a default value of json. Therefore the API will return results in a JSON string unless otherwise specified.

Results #

If you didn’t specify the format or you chose json, you will see something like below:

{
  "email_address": "test@test.com",
  "domain": "test.com",
  "is_free": "True",
  "is_syntax": "True",
  "is_domain": "True",
  "is_smtp": "True",
  "is_verified": "False",
  "is_server_down": "False",
  "is_greylisted": "False",
  "is_disposable": "False",
  "is_suppressed": "False",
  "is_role": "False",
  "is_high_risk": "True",
  "status": "False",
  "credits_available": 297,
  "error_code": "",
  "error_message": ""
}

If you chose xml explicitly, then you’ll see the below:

<response>
	<email_address>test@test.com</email_address>
	<domain>test.com</domain>
	<is_free>True</is_free>
	<is_syntax>True</is_syntax>
	<is_domain>True</is_domain>
	<is_smtp>True</is_smtp>
	<is_verified>False</is_verified>
	<is_server_down>False</is_server_down>
	<is_greylisted>False</is_greylisted>
	<is_disposable>False</is_disposable>
	<is_suppressed>False</is_suppressed>
	<is_role>False</is_role>
	<is_high_risk>True</is_high_risk>
	<status>False</status>
	<credits_available>296</credits_available>
	<error_code></error_code>
	<error_message></error_message>
</response>

Whichever format you choose, the results are still the same. So select whichever works best in the programming language that you need.

For more info on the API, check out the API documentation page.

Auto renewal #

The MailboxValidator API plans are all operating on a 30-day cycle. This means the credits you have purchased must be used up within 30 days of purchase or they will be forfeited. At the end of the 30 days, your stored credit card will be charged and your subscription to the API will be auto renewed. You can unsubscribe at any time via the MailboxValidator user area after you have logged in.

Auto recharge #

If you have used up your credits before the end of the 30-day cycle, our system will auto recharge your credits to the full amount as per your subscribed plan. Your stored credit card will then be charged and your 30-day cycle begins again.

Upgrading or Downgrading Your Plan #

If you require more credits per billing cycle, simply log into the user dashboard. Next, click on the Upgrade option and select your new tier.

Conversely, you can opt to reduce your plan if you require fewer credits. To do this, click on Downgrade and choose a smaller package.

These two actions do not apply immediately. Instead, they are scheduled to become effective at the start of your next billing cycle. Furthermore, you can easily cancel these pending changes anytime before the current cycle ends.

Canceling Your Subscription #

Alternatively, you may wish to stop all future charges to your credit card. For this reason, you can simply click on the Unsubscribe button.

Please note that this action takes effect instantly. Therefore, your subscription will be immediately terminated and your API access will be disabled right away.

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