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The power of Email Validation API

Aug 27, 2020

Have you ever dreamt of a frictionless registration flow for your users?
One without a need to double type their email address, do the double opt-in, use CAPTCHAs. One that would seamlessly drivein no-time your user through the necessity of leaving contact info, and let them enjoy the awesomeness of your product or service?

Email Validation?

But it’s risky, you might say. Studies show that up to 10% of email addresses are incorrect at the moment of entry. Obviously with higher numbers for users of mobile devices (fat finger thing). Additionally, some of users prefer to leave disposable email addresses, when just getting to know us.

This may cause some problems, raise the cost of our operations and decrease customer satisfaction. Obviously, a typo in an email address of our customer will not leave them happy, when they wait to hear from us.

Some will decide to reach out, but this will increase our support cost and will put additional effort on the user.

Others will forget about it or even irritated simply leave.

Additionally, undeliverable email addresses in our database will result with bounce back, will increase bounce ratio and may lead to us being listed on blacklists and cause the whole email deliverability drop.

How to find a good balance then? Email validation API might be the answer.

What is Email Validation API?

Email validation API is a simple way of utilizing the power of email verification and validation within your system or a website, so you don’t have to worry about all the bits and pieces and you can leave it to the Email Validation API service provider who knows how to do that well.

Usually, API (application programming interface) is in a form of HTTP-based RESTful API. Best Email Validation provides various methods and endpoints, and most of them always provide at least Real-time Email Validation API endpoint.

How does Email Address Validation API work?

In a nutshell, whenever your system sends a request through an API to validate and verify an email address multiple checks will happen in just fractions of the seconds to give you the most accurate answer if the email address is a valid and deliverable one.

Starting with the simple ones like:

  • Check the syntax of an email address, and if it follows formal definitions posted in RFC 5322 and RFC 5321,
  • DNS record checks – searching for MX and A records,
  • Verification if an email address is disposable (also known as temporary), registered by a free email provider and if it is a functional, shared email address or distribution group.

Next, API service providers will:

  • Establish a short connection with the recipient’s email server,
  • Negotiate with the recipient’s email server if the email address is registered there,
  • Analyse the communication, react to email service provider requirements and comply with proper protocols,
  • If needed react to grey-listing situations and needs to make retries.

Best Email Validation API service providers will additionally do all of that:

  • Without sending actual email messages,
  • Respecting email service providers infrastructure by minimising the footprint and resource utilisation,
  • Having on top of the mind Data Security aspects.

How to use Email Validation API

The simplest way to use the Email Validation API is to connect to Real-time Email Validation API endpoint.

Here’s the example of usage utilising cURL:

curl https://api.usebouncer.com/v1/email/verify?[email protected]&timeout=30
-H 'x-api-key: API-KEY'

It calls:
– Bouncer’s Real-Time Email Validation API endpoint (https://api.usebouncer.com/v1/email/verify)
– with parameter ?email= where we can put an email address to be verified,
– with parameter &timeout= where we can put the maximum expected amount of seconds within which we want to receive results (values between 1-30 with default=10)
– -H ‘x-api-key: API-KEY’ – header information where we put our API-KEY received from Bouncer.

Email Validation API will return results in a form of JSON following this schema:

  "email": "[email protected]",
  "name": "John Doe",
  "status": "deliverable",
  "reason": "accepted_email",
  "domain": {
    "name": "usebouncer.com",
    "acceptAll": "no",
    "disposable": "no",
    "free": "no"
  "account": {
    "role": "no",
    "disabled": "no",
    "fullMailbox": "no"

All the detailed information, terminology and the guidelines can be found in the Bouncer’s WebApp -> API Panel.

Best Email Validation API also provides capabilities of validating and verifying email addresses in bulk with its Bulk Email Validation API endpoints.

Such APIs usually give a possibility to create a request, check the status of a request, download the results, and even provide callback_url if needed.

If you’d like to brainstorm on the development – let’s talk.


Using Email Validation API PHP example

Here you can find an example of Email Validation API PHP implementation:

public function verifyEmailRealTime($email)
$emailEncoded = urlencode($email);
$apiKey = “YOUR_API_KEY";
$apiURL = "https://api.usebouncer.com/v1/email/verify";
$fullURL = $apiURL."?email=".$emailEncoded;
// Get cURL resource
$curl = curl_init();
$headers = array(
'x-api-key: '.$apiKey
curl_setopt_array($curl, array(
// Send the request & save response to $resp
$resp = curl_exec($curl);
// Close request to clear up some resources
return $resp;


The power of Email Address Validation API – possible use cases

Our customers have been successfully using Bouncer’s Email Validation API in many different use cases and forms, however the most common ones were.

Email Validation on registration and sign-up forms to prevent typos

One of the most common ways of utilizing Email Validation API is enabling it during the registration flow. This way we can make sure that the mistyped email address is being spotted right away, and our user can correct it immediately.

You can choose a different approach to that and check email address when user:

  • stops typing for X seconds,
  • gets out of the email address field,
  • clicks submit button,
  • or after user clicks submit button and letting them know in the next step that email address might need corrections.

A sample usage flow might look like on the chart below:

Email Validation in the pop-up windows to prevent typos

You also could incorporate Email Validation API to check email addresses in the pop-up windows that call to leave the email address. Pop-up windows are a bit intrusive – why not make the process as simple to the user as possible?

Email Validation to prevent registrations with disposable email addresses

If you’d prefer rather not to allow disposable, temporary, 10-minute emails into your system – you could utilize information about such a fact provided by the Email Validation API.

Email Validation to prevent free emails from sign-up

If you are for example running a B2B business, and you’d prefer only to store business emails – you could utilize information about free email addresses provided by the Email Validation API, and ask your user to provide another address of theirs.

Email Validation of contact lists uploaded by your user

If your own IT system is allowing your users to upload multiple email addresses at once, you could consider utilizing a power of Bulk Email Validation API.

The flow could be as follows:

1. User uploads their email addresses list,

2. Your system creates an Email Verification Request with Bouncer and also provides callback_url that will be waiting for information about finished email verification.

3. Your system informs user that the email list is being verified and that they will be able to continue once verification is finished.

4. Just in case your system checks (for example every minute) the status of email list verification.

5. When bulk email verification is finished, your system downloads the results and lets your users take proper actions with the ones that are undeliverable (remove contacts, remove addresses, correct addresses etc.)

With that kind of solution in place, you’ll make sure that only valid email addresses enter your database.

Email Validation before mass send-outs

If you want to fully protect your email infrastructure of your own IT systems you might want to consider utilizing the power of Bulk Email Validation API before bulk email send-outs.

The solution could be as follows:

1. You create a buffer for emails to be sent – this is a place where emails scheduled by your users land,

2. When it’s close to the planned send out – your system takes a batch of email addresses to be verified,

3. Your system creates an Email Verification Request with Bouncer and also provides callback_url that will be waiting for information about finished email verification.

4. Just in case your system checks (for example every minute) the status of email list verification requests.

5. When bulk email verification is finished, your system downloads the results.

6. For email addresses that are undeliverable – puts the send-out on hold and informs the users which messages could not be sent.

How to pick the best Email Validation API provider?

While partnering with Email Address Validation API service providers, you should look for factors like:

Trustworthiness and security

Check if the provider is a legally registered company. It’s good to see if there are some people behind it. Verify what’s their approach to data security, where do they host their servers, with whom do they share the data, and who do they choose as subprocessors.

Performance and precision

Obviously Real-time Email Validation API has to be super fast, so that your users don’t have to wait. This makes Email Validation Service to rush, and the question is what choices will it make while rushing.

Will it jeopardize the quality of results in order to give any result, or will it be honest to say “I don’ know… thus return unknown”. If they choose the latter it would be good to check what’s the average percentage of “unknown” results – a good score would be less than 5-7%.

On the other hand – it would be good to check what’s the median of processing time – to understand the performance.

Flexibility and ease of use

Time, energy and talent of your Team is most likely the most precious asset of yours.
Thus it’s important integrating with Email Address Validation API will not take too much time of theirs, and will be as simple as possible.

It would be great if an Email Validation Service provider is willing to support you during the process of designing, implementing and testing the solution.

It’s also important to have possibilities and a lot of flexibility – technology should not limit us but be there for us. With that said, the abundance of different endpoints and methods of Email Validation API is always a plus – but still have to be simple.

How is Bouncer different from other Email Validation tools?

We are a team of very humble people but need to be proud of what we’ve created.
That’s why I’d like to share few of our differentiators

Scalability and performance

Our Email Validation Services are designed to be super scalable and high performing, as we created Bouncer to be API first.

Quick and easy implementation

After super simple registration process (we had to create it as frictionless as possible, right?!), in seconds you’ll get everything you need to get started.

Basic email validation use cases can be implemented in just a few hours (including the whole end to end integration tests).

The more sophisticated applications should not take more than couple days of development, and will be happy to support you during the whole process – we’ll even dedicate our people to be fully accessible to you over that period.

Precision and Security

Bouncer has one of the lowest “unknown” ratios and at the same time one of the highest precision on the market.
All of that without any compromises to the security.

We’re using only AWS European data centers for data processing and data storage. We even when an extra mile and decided to anonymize email addresses in all the parts of our system (including logs from communication with SMTP servers!).

We are the only ones on the market who did not take the shortcuts and do not allow to pass API Key in the url – you’ll need to use the header for that.

Premium caring support

We are truly Human to Human organization, we do our best to support you during the whole journey with us.


Our solution and Email Validation API are truly flexible, cause we are – we believe we will be able to accommodate any of your Email Validation and Verification needs.


And for the techy of you… we’ve got a pretty cool modern tech stack. The architecture is based on self-discovering microservices, fully scalable and fully flexible for changes too… this actually is one of our hidden gems. It’s a result of a lot of genius put into R&D.

If you’d like to talk Tech – we’d love to chat with you.

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