Last updated
August 1, 2023

Real-Time Email Validation: Best Practices, Tools and Benefits

Elizabeth (Lizzie) Shipton

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Just looking for the best tools? Jump to the best real-time email validation tools.

In this article, you'll learn:

  • Email validation is crucial to ensure email deliverability and prevent fraud.
  • Real-time email validation allows for immediate feedback on email addresses.
  • Benefits of real-time email validation include reduced bounce rates and improved sender reputation.
  • Real-time email validation can be performed using an API or a library.
  • When choosing a real-time email validation provider it's important to consider accuracy, speed, and integration options.

Real-time email verification is the process of validating an email address at the point of entry. Meaning, ensuring that the email is valid at the moment a user signs up for your service or fills out an online contact form.

The benefits of real-time email verification are numerous: it prevents bad actors and fake emails from polluting your list and gives you less work to do later when it comes time to clean your mailing list. It also improves your open rates and sender reputation, as it prevents you from ever sending an email to an address that won't open it or doesn't exist.

In this article, we'll break down exactly what real-time email verification entails, and look at some of the best ways to do email verification and validation so that only valid email addresses make it onto your mailing list.

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Understanding Email Verification and Validation

Email validation involves examining email addresses to determine that those addresses are real and active. There are many ways in which an email address can be invalid: there could be typos in the address, the address could be a temporary address, there could be an issue with the domain, or the address could simply be unused.

Here are some of the most common things to check for you to verify email addresses:

  • Syntax errors - misspelled words, particularly domain names, and improper formatting
  • SMTP verification - ensuring that the mailbox for the address is able to receive mail
  • Free or disposable addresses - these are fake addresses that people use to sign up for services and then never use again
  • MX record checks and domain verification - ensuring that the domain of the email address exists and is a valid domain

There are a few ways to check these things - for example, you could use Regex to pattern match and look for formatting issues, or you could ping the mail servers of the address to check for deliverability.

You could perform these checks at any time. In fact, you should be doing regular cleaning of your mailing list to purge invalid email addresses. However, doing real-time validation the moment users enter their addresses into your sign-up forms is the best way to verify email addresses and keep invalid addresses from getting through.

Benefits of Real-Time Email Verification

There are many benefits to using a real-time verification API to check email addresses at the moment users sign up for your mailing list or service. Catching these invalid emails before they get onto your list means you'll never send an email that bounces or ends up in a spam folder.

Here are the main benefits of using a real-time verification API:

  • Better engagement and higher open rates - from the get-go, your emails will be going to users who will actually open them. This improves engagement with your brand and increases your open rates.
  • Reduced bounce rates and spam complaints - similarly, fewer emails will bounce because every address on your list will be an active and verified address.
  • Increased email deliverability - higher open rates and reduced bounce rates lead to increased email deliverability because your messages are less likely to end up in a new user's spam folder.
  • Improved sender reputation - increased email deliverability leads to improved sender reputation, which makes new domains more likely to accept your emails.
  • Higher conversion rates and ROI - it goes without saying that having a list full of engaged users who want your emails will lead to better conversion rates and greater ROI for each email sent.

In addition, real-time email verification saves time and money. If you pay for an email service provider to handle sending messages to your subscriber list, you likely pay more once you hit a certain number of subscribers.

When you're paying to keep people on your subscriber list, you want to make sure that investment is paying off. If your list is full of fake email addresses and invalid email addresses, you're essentially paying to keep useless emails on your list.

Real-Time Email Verification Tools

There are a few lines of defense against invalid email addresses. You could roll your own email verification tool, use a package or library for whatever language or framework your app or website is built in, or load your list into an Excel sheet to run validation checks.

You could also use an online email verification API.

Best Email Validation APIs

These days, there are so many cheap and even free options for online services out there, that it doesn't make sense to build your own. Let's take a quick look at some of the best email validation API options.


AbstractAPI is an API company that provides a range of APIs for various tasks such as email verification, image processing, phone number validation, and others. (We're admittedly bias here).

For email verification, AbstractAPI maintains a comprehensive database of known disposable and free email accounts to help verify and block email addresses more accurately.

Get started with a free account that allows up to 100 requests per month, which we believe is a generous offer. For more significant needs, we provide monthly subscription plans starting at $9/month, allowing validation of up to 5000 invalid email addresses.


ZeroBounce is an email verification service that specializes in email list cleaning. In addition to their bulk email verifier, they maintain an API that is accessible via REST request and secured with an API key.

They offer a free trial period of one month, during which time you can validate up to 100 email addresses. From there, prices start at $0.08 for 2,000 bulk email validations, or $0.075 per email verification if you purchase a monthly subscription.

Email Checker

This email verification API is completely free and may be a good option for small businesses or developers looking to test an application or website. They can check for fraudulent and invalid email addresses one at a time.

The downside to this service is that they are unable to do bulk email list verification, or to check email addresses in real-time via an API call. The service only works for one email address at a time, from a list you already own.


This email verification service is the best verification API for an affiliate management company. They offer bulk email list verification, a real-time email verification API, and IP blacklist monitoring.

Their prices are similar to ZeroBounce, at around $70 per 10,000 addresses verified. They offer a similar free tier that gives you up to 100 free validations per month.


BriteVerify is made by Validity and is one of the longest-standing email verification tools around. They process 1.5 million email addresses every 24 hours and offer generous pricing at $0.01 per email for up to 250,000 emails.

BriteVerify can remove duplicate email addresses and do domain validation, as well as spot invalid addresses in real-time.


NeverBounce is similar to ZeroBounce, and people understandably confuse these two services. However, NeverBounce has a slightly different offering and pricing structure to ZeroBounce. They do not offer a free trial, instead allowing you to test just one email in their online verifier.

NeverBounce's prices are very reasonable: just $0.008 per email for up to 10,000 email addresses, or $10 per month for up to 1000 addresses. They offer a monthly subscription to clean an existing list or to access their real-time email verification API.

How to Validate Email Addresses in Real-Time With AbstractAPI

Let's take a look at one of these services and learn how to integrate email verification API tools into your app or website.

Get Started With the API

In order to use the Abstract Free Email Validation API, you'll have to sign up for a free account and receive an API key. This key authenticates you and allows you to make requests to the API endpoints.

Navigate to the home page and click "Get Started"

Once you've signed up or logged in, you'll be taken to the API dashboard. You'll see your API key, plus links to documentation and pricing, as well as a testing sandbox.

Send a Test Email Validation Request to the API

Click on the testing sandbox and choose your preferred language. For this article, we'll look at Javascript. In the sandbox, you'll see a block of code that you can simply copy and paste into your own application.

function httpGetAsync(url, callback) {
const xmlHttp = new XMLHttpRequest();
xmlHttp.onreadystatechange = function() {
if (xmlHttp.readyState === 4 && xmlHttp.status === 200)
}"GET", url, true);

const url = ""


This simply sends a GET request to the API with a single email address included as a querystring parameter for verification. Your API key is also included as a querystring parameter.

The response you get from the API will look something like this:

"email": "",
"autocorrect": "",
"deliverability": "DELIVERABLE",
"quality_score": "0.80",
"is_valid_format": {
"value": true,
"text": "TRUE"
"is_free_email": {
"value": false,
"text": "FALSE"
"is_disposable_email": {
"value": false,
"text": "FALSE"
"is_role_email": {
"value": false,
"text": "FALSE"
"is_catchall_email": {
"value": true,
"text": "TRUE"
"is_mx_found": {
"value": true,
"text": "TRUE"
"is_smtp_valid": {
"value": true,
"text": "TRUE"

As you can see, AbstractAPI checks for a few things when it looks for invalid email addresses:

This is an extremely thorough email verifier service. You can pull out any or all of these fields from the JSON response to determine validity in your own code. For example, if role-based emails are not a critical issue for you, you can simply ignore this field.

Let's take a look at some sample code that you could use to use these fields to verify emails.

const API_URL =
"" + API_KEY;

const sendValidationRequest = async (emailAddress) => {
const fullURL = API_URL + "&email=" + emailAddress;
const apiResponse = await fetch(fullUrl);
const data = await apiResponse.json();
const isValid = data.is_valid_format.value;
return isValid;

This only looks at the is_valid_format field, and ignores all other validity checks. The is_valid_format field only deals with syntax and formatting issues. For a more thorough check, you could pull more fields out of the JSON response and check their values.

Best Practices for Real-Time Email Verification

In order to get the most out of real-time email verification tools, you should establish some practices you make things easier for yourself.

The most important thing you can do to make email verification easier is to automate it as much as possible. Integrating an email verification API into your application and sign-up forms is a great way to do this. Send the verification request as the user inputs their address into a form input, and don't allow a user to subscribe to your list if the address is not valid.

It's up to you to set thresholds for what is considered valid. An API like Abstract returns to you information about the success of different validity checks. You may want to use all of these to determine whether an address is valid or use only some.

In addition to this, you should still be doing bulk email list verification on a regular basis. If possible, you should automate this too. It will be up to you to determine the right frequency at which to run bulk email list verification, but a general rule of thumb is to do it once every 6 months.

Most of the services listed above offer bulk email list verification in addition to real-time validation. Some of them also offer a monthly subscription for doing email list cleaning.

Case Studies

Here are just a couple of examples of companies that have benefited from integrating real-time validation services into their email marketing platform.


MediaShares was experiencing such high bounce rates that their email service provider canceled their service. At one point, their bounce rate was as high as 12%.

They ultimately settled on ZeroBounce to handle their email verification needs. MediaShares states that ZeroBounce was not only the cheapest option but also the most accurate, and came with great customer service.

With ZeroBounce's help, MediaShares was able to reduce its bounce rates to nearly 0.


The email verification service Kickbox helped MuleSoft to run an audit of their email database to determine the volume and sources of their bounces. It was discovered that their average deliverability rate was as low as 90% and that many of their email addresses, while valid, were role-based, free, or temporary addresses.

With Kickbox's help, MuleSoft was able to improve its deliverability score to 99% and remove many of the low-quality email addresses from its database. They also set up real-time validation that prevented users from using temporary emails or fake addresses to sign up.

Choosing the Right Email Validation Provider

When choosing an email verification platform, there are a few factors to keep in mind. First of all, you should consider the size of your business and the volume of emails you anticipate needing to verify.

While a big, reputable company like XVerify might offer a very attractive service, it may be overkill for a small business. On the other hand, a large company with a high volume of users will quickly outgrow the free offering of a service like Email Checker.


What is real-time email verification?

Real-time email verification allows you to validate and verify email addresses as they are typed into an input form. Done correctly, it prevents temporary emails, fake addresses, misspelled addresses, and other low-quality email addresses from getting onto your mailing list.

How do you verify if an email address is real or fake?

There are several ways to identify fraudulent and fake email addresses. You should check the syntax and formatting of the address for typos and spelling mistakes. Next, check the address against a database of known free or temporary emails.

You should also examine the domain of the address to make sure that MX and SMTP records are up to date. Finally, you'll need to check known spam traps and IP blacklists.

There are many online email verification tools out there to help you do all of these things quickly and easily.

What is the best email verification tool?

The top email verification tools available online are AbstractAPI, Zerobounce, NeverBounce, XVerify, BriteVerify, and Kickbox.

Elizabeth (Lizzie) Shipton
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