Last updated
August 1, 2023

How to Verify an Email Address and Ensure Accuracy

Elizabeth (Lizzie) Shipton

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Email verification is a critical component of successful email marketing. An email list is useless if it is full of invalid email addresses, fake email addresses, inactive email addresses, or other undeliverable address types. In this article, we'll talk about what email verification is, why it's important, and some email verification methods.

Key takeaways:

  • Email verification is the process of validating that an email address is legitimate and deliverable.
  • Verifying email addresses is important to avoid spam traps and increase engagement, and improve sender reputation.
  • There are several ways to verify email addresses, including syntax checks, DNS lookup, SMTP server verification, spam trap detection, role-based email detection, and temporary email detection.
  • Email addresses can be verified in real-time when a user signs up, or in bulk by running an email verification tool on a CSV list of addresses.

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Why Should You Verify Email Addresses?

If you run a mailing list or use email campaigns to promote your services or products, you should be verifying every single email address that tries to make its way into your database. Invalid addresses are the number one cause of high bounce rates, which hurt sender reputation and increase your chances of your emails ending up in a spam folder.

The average email bounce rate is somewhere between 1 and 2%. Usually, if your list is healthy, your bounce rate will be much lower than that. If your email bounce rate is between 2 and 5%, it could mean you have a problem with your list - lots of invalid email address instances, for example. If your bounce rate is higher than 5%, you should take immediate action to remedy the situation.

Remedying the situation could mean utilizing an email verification tool to ensure that the email addresses on your list are accurate and valid. An email verification tool can help you detect spam traps and remove remove invalid email addresses.

You should verify email addresses in real-time, at the moment users attempt to sign up via an online form or weblink. You should also verify email addresses regularly in bulk by using an email verification service to check all the email addresses on your list.

Best Ways to Verify an Email Address

There are several tools out there to help you verify email address instances and ensure that your list contains only valid email addresses. These services do a number of things to ensure that an email address exists, including syntax checks, DNS lookup, SMTP verification, and detection of role-based, free, and temporary email addresses.


The AbstractAPI Free Email Validation API provides a simple REST endpoint secured by an API key, that allows you to upload email addresses for validation. You can use the endpoint to validate email addresses in real-time, or you can upload your email list as a CSV file to bulk verify email address instances.

The free tier allows up to 100 requests per month and is great for testing and development. From there, prices start at $9/month for 5000 requests per month, up to $499/month for up to 750,000 requests.

Get Started With the API

Let's take a quick look at how to use AbstractAPI to validate an email address in real time (i.e. when a user attempts to sign up for your mailing list via an online form.)

Acquire an API Key

Navigate to the API Get Started page. You’ll see an example of the API’s response object. Click the blue “Get Started” button

If you’ve never used AbstractAPI before, You may need to provide your email address and create a password.

You’ll be taken to the API’s homepage, where you’ll see options for documentation, pricing, and support. Here's where you'll find your API key.

Use Your API Key to Send a Request to the API

Let's assume we're sending a request from our app or website frontend to validate an email at the moment a user enters it into a form. The email verification process for this particular use case is very easy.

Using Axios, or a similar AJAX request module, we can write a function to send a network request to the API. The request should include the email address we want to validate as a parameter. The API will return a JSON response containing data that will help us determine if the email is valid.

import axios from "axios";
const apiKey = 'YOUR_API_KEY';
const apiURL = '' + apiKey
const sendEmailValidationRequest = async (email) => {
try {
const response = await axios.get(apiURL + '&email=' + email);
} catch (error) {
throw error;

The response you get from the API should 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, Abstract uses a lot of factors to determine email deliverability. The API looks for syntax errors, then checks MX records, SMTP, and runs checks to determine if the address is a role-based email, free email, or temporary email account.

You can use any or all of these checks to make your own validity assessment. For the sake of this tutorial, let's just use the is_valid_format field to make sure there are no syntax errors in the address. We'll return the value from that object and use it in a validation function.

const response = await axios.get(apiURL, { api_key: apiKey, email });

Other Methods

Let's delve into some of the ways in which services like Abstract do email validation.

syntax check

The first step in verifying a recipient's email address is looking at the address itself. Users frequently misspell things. While it's not possible to catch typos in the username portion of an email address (the part before the '@' symbol) it is possible to catch syntax errors in the domain name (the part after the '@'.)

There are also certain symbols that are not allowed in email addresses. If these symbols exist in the username portion of an email address, it's possible the user could have misspelled their username. It's also possible the user could be a bot or a bad actor trying to gain access to your email list.

Services like Abstract run email syntax checks to catch common misspellings in domain names, such as 'gamil', 'yhaoo', etc.

dns lookup

The next step to verify an email address is valid is to check the DNS records - otherwise known as domain verification. DNS stands for Domain Name System, and it is the process by which human-readable web addresses like are turned into computer-readable IP addresses like

In order for email to be delivered, the email address in question must have DNS records filed with the mail servers.

A DNS MX (Mail Exchange) record lays out how emails should be routed to a DNS server. The records ensure that mail is being delivered in accordance with SMTP.

smtp verify

SMTP stands for Simple Mail Transfer Protocol, and it governs how email is sent and received around the web, similar to the way HTTP (Hyper Text Transfer Protocol) governs how websites are requested and delivered to users.

In order for an email to be delivered, it must pass through an SMTP server. SMTP verification checks that the given email address actually exists at the mail server to which it is being delivered.

role-based email detection

Role-based emails are addresses that belong to a business domain but are not assigned to a specific employee. Examples include 'help@', 'info@', 'support@', etc. These addresses are problematic to have on your list because they often go to automated systems that will not reply and could even bounce the email back.

Email verifier services like Abstract are able detect these types of email addresses so you can remove them from your database.

disposable email address detection

Disposable email addresses are typically used by people to sign up for mailing lists in order to get a free giveaway item (a reader magnet or coupon, for example) without having to provide their real email address and receive mail from the list. The address is usually only valid for a few minutes or hours - long enough for the user to get the free item delivered.

There are lots of disposable email service providers out there, and unfortunately, more are being created every day, so it can be difficult to detect these types of emails on a mailing list. However, most email verification tools online will run a check to try and catch these types of addresses.

catch-all email verification

A catch-all email address is an address belonging to an email server or a business domain that is intended to catch any incoming emails that are addressed incorrectly or are somehow invalid, but are still intended to go to the domain.

These addresses are useful for businesses who need to ensure that all emails get through to their servers so they don't miss any leads or customer issues. However, if one of these email addresses ends up on your mailing list, it could hurt email deliverability and and ding your sender reputation.

An email verification tool like Abstract will be able to root out these catch-all emails so you can remove them from your list.

The Importance of Email Deliverability

Deliverability issues and high bounce rates are the number one things that impact sender reputation. Sender reputation is what determines whether your email messages will make it to new recipients.

The Impact of Email Verification on Deliverability

If your emails are regularly failing to deliver because addresses on your list are invalid, it will lead to future issues as mail servers decide that the emails you are trying to deliver are not wanted by users, and send them to spam.

How email verification affects inbox placement

Inbox Placement Rate (IPR) is the percentage of emails that were successfully delivered to users, rather than ending up in spam, promotions, or junk folders. Your IPR is a determining factor in your sender reputation, which is used by email service providers to decide whether they should allow your messages to make it to users' inboxes.

Reducing bounce rates and improving sender reputation

Reducing bounce rates and improving your IPR will lead to an improvement in sender reputation. The easiest way to improve your bounce rate is to remove invalid and undeliverable email addresses from your list.

Avoiding Spam Traps and Blacklisting

Another issue in email deliverability is the prevelance of spam traps and blacklists.

Understanding spam traps and their consequences

A spam trap is an email address set up by an email service provider specifically for the purposes of catching spam messages. These emails are a useful tool for identifying bad actors and senders who aren't following best email practices.

Unfortunately, if one of these spam trap addresses ends up on your list, it could lead to your legitimate email messages being marked as spam. It's important that you identify and remove these addresses from your list as quickly as possible to avoid harming your sender reputation.

Techniques to prevent blacklisting

An email blacklist is a collection of IP addresses that are believed to send spam. Messages from these addresses are usually blocked or sent straight to spam. Blacklists are identified by spam traps.

The best way to avoid ending up on an email blacklist is to require strong passwords from your users, make sure your SMTP records are up to date, avoid using email relays, and verify all email addresses before they come onto your list.

Best Practices for Email Verification

Follow these tips to ensure that your email verification efforts are successful.

Capturing Correct Email Addresses

Real-time validation is your first and best defense against invalid addresses. It's impossible to ensure that no invalid addresses make it through, but you can do a few things to catch 90% of user mistakes and problems.

Employ user-friendly forms and validation techniques

The best way to prevent invalid addresses from making it onto your list is to build high-quality forms using modern frameworks. These frameworks autofill forms, handle errors, catch typos, and allow you to build-in a real-time verification process.

Implement verification during the sign-up process

As well as relying on built-in form methods to autofill, catch syntax errors, and ensure that required fields are completed, you should be utilizing a real-time email verification service like AbstractAPI to receive network requests and do email verification for every address that is input into your form.

Batch Email Verification

The next step in ensuring that your email list stays healthy and engaged is to do regular bulk email verification of your entire list. This will allow you to detect and remove any invalid addresses that slipped through the cracks during sign-up.

Verifying large email lists efficiently

Many online services provide bulk-upload options that run verification procedures on all the emails on your list. AbstractAPI, for example, provides a bulk upload interface that accepts a CSV file of email addresses to verify, and returns an email with a downloadable CSV file containing the verification results.

Maintaining a Clean Email List

For best results, bulk verification should be done regularly to purge invalid addresses and ensure high sender reputation. At the very least, you should use a tool like AbstractAPI's bulk email validator to examine your list every six months.


Email campaigns are some of the most effective marketing tools available to online businesses. However, in order for your campaigns to be successful, you must be delivering messages to inboxes that can receive them.

Your sender reputation is determined by your past deliverability scores, including your Inbox Placement Rate. If many of your messages are being delivered to invalid accounts or bouncing because accounts have become inactive or no longer exist, you will have a low sender reputation and your outbound emails to new clients may not be delivered.

Use email verification tools like Abstract API's Free Email Verification API to verify an email address in real time as a user inputs it into a form, and use bulk email verification tools to verify email lists regularly and purge inactive and invalid addresses.


How accurate is email verification?

The accuracy of email verification depends on the service being used to verify the addresses. Some services are very good at detecting spam traps, role-based emails, catch-all emails and other types of invalid addresses, while others are not so good.

Can email verification detect typos?

Yes, the best email verifier tools can easily detect typos in domain names, and unexpected characters in usernames.

Is email verification 100% foolproof?

No. There is no 100% foolproof method to verify emails. New free and disposable address servers pop up all the time, users make mistakes, and spam traps are prevalent. However, using an email verifier will greatly improve your chances of your emails making it to a recipient's inbox.

How often should I verify my email list?

You should run checks on your mailing list at least once every six months, and you should do real-time validation to check every new email address that attempts to join your email list.

Elizabeth (Lizzie) Shipton
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