2.0.4 • Public • Published

Kickbox Email Verification Service

Email Verification Library for Node.js

Kickbox determines if an email address is not only valid, but associated with a actual user. Uses include:

  • Preventing users from creating accounts on your applications using fake, misspelled, or throw-away email addresses.
  • Reducing bounces by removing old, invalid, and low quality email addresses from your mailing lists.
  • Saving money and projecting your reputation by only sending to real email users.

Getting Started

To begin, hop over to and create a free account. Once you've signed up and logged in, click on API Settings and then click Add API Key. Take note of the generated API Key - you'll need it to setup the client as explained below.


Make sure you have npm installed.

$ npm install kickbox


Works with Node 0.8+


var kickbox = require('kickbox').client('Your_API_Key_Here').kickbox();
kickbox.verify("", function (err, response) {
  // Let's see some results


timeout integer (optional) - Maximum time, in milliseconds, for the API to complete a verification request. Default: 6000.

// Example with options
kickbox.verify("", {timeout: 6000}, function (err, response) {/*...*/});

Response information

A successful API call responds with the following values:

  • result string - The verification result: deliverable, undeliverable, risky, unknown
  • reason string - The reason for the result. Possible reasons are:
    • invalid_email - Specified email is not a valid email address syntax
    • invalid_domain - Domain for email does not exist
    • rejected_email - Email address was rejected by the SMTP server, email address does not exist
    • accepted_email - Email address was accepted by the SMTP server
    • low_quality - Email address has quality issues that may make it a risky or low-value address
    • low_deliverability - Email address appears to be deliverable, but deliverability cannot be guaranteed
    • no_connect - Could not connect to SMTP server
    • timeout - SMTP session timed out
    • invalid_smtp - SMTP server returned an unexpected/invalid response
    • unavailable_smtp - SMTP server was unavailable to process our request
    • unexpected_error - An unexpected error has occurred
  • role true | false - true if the email address is a role address (,, etc)
  • free true | false - true if the email address uses a free email service like or
  • disposable true | false - true if the email address uses a disposable domain like or
  • accept_all true | false - true if the email was accepted, but the domain appears to accept all emails addressed to that domain.
  • did_you_mean null | string - Returns a suggested email if a possible spelling error was detected. ( ->
  • sendex float - A quality score of the provided email address ranging between 0 (no quality) and 1 (perfect quality). More information on the Sendex Score can be found here.
  • email string - Returns a normalized version of the provided email address. ( ->
  • user string - The user (a.k.a local part) of the provided email address. ( -> bob)
  • domain string - The domain of the provided email address. ( ->
  • success true | false - true if the API request was successful (i.e., no authentication or unexpected errors occurred)

Response headers

Along with each response, the following HTTP headers are included:

  • X-Kickbox-Balance - Your remaining verification credit balance (Daily + On Demand).
  • X-Kickbox-Response-Time - The elapsed time (in milliseconds) it took Kickbox to process the request.



Bug Reports

Report here.

Need Help?


npm i kickbox


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  • danhstevens
  • schaitanya