How To Verify An Email Address And Choose The Best Email Verifier

email verification

So, you’ve used email address lookup tools and finally grown your list big enough, and it’s time to learn how to verify email addresses to keep that list clean. Congratulations! 

Email verification is one of the most important steps in email marketing, right after building your list of leads. Which is why we have devoted this whole article to email verification, why you shouldn’t neglect it, what types of email testers exist, and how to choose the best one.

Note, this is a complete, comprehensive guide to email verification. We will keep monitoring the relevancy and accuracy of the data included, and updating the article as necessary.


What is email verification (and how is it different from email validation)

If only you knew how much time and effort it took me to find out the exact difference between these two.

Online, in every blog and on every website, people use verification and validation interchangeably, often giving these words their own definition. We, too, prefer to use these interchangeably, however, the correct definition is slightly more precise.

Email verification is the process of checking an email address for being existent and active, aka valid. A valid email is one that can receive messages from other senders. Every email verifier, either bulk or single, performs (or is at least supposed to) multiple steps of the verification process. The most common are the syntax, domain, catchall, and MX record checks, and email address ping (you will read about them in detail further on in the article). 

Email validation is the final result of the email verification process that’s provided to the user. Depending on that result, an email gets one of the email verification statuses, usually “valid”, “invalid”, and “unverifiable”. Sometimes, validation also implies checking any additional information that comes with the lead’s email, or checking the source of that lead.

How an email verifier works

There are lots of technical nuances to how email verifier tools work. The general idea is that every email tester performs verification according to the algorithms the developers have put in it. For example, our email verifier goes through 7 steps of email verification for maximum accuracy:

  • syntax check
  • gibberish check
  • domain existence check
  • MX record check
  • catch-all domain check
  • SMTP authentication (email address ping)
  • freemail check

Here are the 5 most common email verification steps explained:

1. Syntax check

When you write a professional email, you most likely use an app like Grammarly to check your copy just to be sure every word is spelled correctly and your punctuation is perfect. 

An email verification service does the same. 

Syntax check algorithms look for the following:

  • Email standard correspondence: the local-part, the at-symbol ( @ ), and a domain name with a dot-symbol ( . ) are present
  • Number of symbols: no more than 64 characters are allowed in the local-part
  • Appropriate placement of dots ( . ) and the ( @ ) symbol 
  • Special characters: ? “ # $ % & ` * + – _  . / | \ ^ {} ~ can be used in the local part of an email address, just not in the beginning or at the end of the local part; (find out more about special characters in email addresses here)

It also checks for common email address syntax mistakes:

  • Periods ( . ) in the beginning or at the end of the address
  • Commas ( , ) instead of periods ( . )
  • Semi-colon ( ; ) or apostrophe ( ‘ ) instead of the at sign ( @ )
  • Spaces or blank areas (   ) in the middle or at the end of the address
  • Double periods ( .. ) in the local part or domain name
  • Missing “.com” or period ( . ) in the address
  • Misplaced at signs ( @ )

2. Domain check

A domain name goes right after the @ symbol and shows which domain the email address is tied to. For example, in, is the domain name. Email verification services check if the domain name is correctly spelled, as well as whether the website and the domain are real and active.

This check is important, if only for one simple reason – websites expire, and so do email addresses tied to them. Some companies leave the market, some migrate to a new domain and create new emails tied to the new domain.

3. Catch-all check

An email verifier also checks if the email belongs to a catch-all domain. A catch-all domain (also known as unverifiable or accept-all) is the type of domain that is set to always accept mail even if you write some gibberish in the local-part of the email belonging to it. 

catch-all email server principle

For example, the domain name is a catch-all. You can keyboard smash and get an email address like that will still accept emails despite being non-existent and random. All email addresses associated with this domain name will accept mail as if real, yet may result in hard bounces as catch-all emails are often set up to avoid unsolicited mail. 

A reliable bulk email verifier (and even an individual email verifier) checks the domain name for being catch-all and notifies you to help prevent bounces. If you see that a verified email is labeled as a catch-all/unverifiable, you can act at your own risk and decide whether you want to send messages to it or delete it from the list once and for all to only send to valid emails. 

4. MX record check

In simple terms, an MX record specifies the mail server that is responsible for accepting emails on behalf of a specific domain. It’s a more complex solution for identifying garbage emails. This feature checks whether the mail exchange entry listed in the email address is an actual, registered and hosted domain name, which can be accessed online.

MX record check is an inevitable step in an email verification process. There are some more technical details regarding this process, but the gist is that to provide correct results, an email verifier has to use an MX record check.

5. Email address ping

During this check an email verifier sends a ping to an email address to see if it is capable of receiving messages and reacting to them. If the request reaches the recipients’ email address and receives a response, an email is considered active and you can safely send real emails to it. This is also known as SMTP authentication.

Why you shouldn’t skip email verification

If you’re still not convinced on why you need to check email accounts, let me show you why email verification matters and why ignoring it when doing email marketing can lead to catastrophic campaign issues that will take weeks to resolve:

Reason 1: Helps keep your email lists fresh

According to a HubSpot report, 22.5% of email addresses become invalid yearly. That’s not your fault, this happens naturally due to various external reasons. Most often it’s because people change companies and their corporate email addresses you have on your list get deactivated. If you don’t verify email lists regularly, in a year, the 22.5% bounce rate will exceed the acceptable bounce rate tenfold (!), and your sender reputation will take a real hit. Pro tip: verify your email list once every two months.

Reason 2: Reduces hard bounces

A hard bounce is an email that returns to the sender because the recipient doesn’t exist, i.e. the email address is invalid. High bounce rates are usually indicative of spammers, which is why ESPs don’t treat users with high bounce rates kindly. When your bounce rate grows, your sender’s reputation falls. Once it crosses a critical threshold, your account gets blacklisted. 

Reason 3: Improves email deliverability 

When you use an email verifier to filter out invalid emails, you can be sure that those that remain are capable of receiving emails, meaning your messages reach the inbox. Subsequently, your email deliverability stays high. This helps save on email sending and, once again, preserves your email sender reputation. Speaking of…

Reason 4: Maintains high sender reputation

Your sender reputation depends on a number of things. We’ve already mentioned bounce rate and deliverability, but there’s also spam report rate and your sender habits (never forget to warm up new email accounts!). Consistently using email verification services in your marketing will help you maintain a high sender reputation and avoid blacklists. Don’t know how to check your sender reputation? Find out here.

Types of email verifiers

Email testers come in many forms and sizes, so it’s not hard to choose an email verification service based on your needs and business type.

Software email verifiers, like AtomPark, can be a good solution for larger businesses where one person will be in charge of lead list management, including verification, as well as businesses consistently working with large volumes of emails. 

The pros are obvious: one-time payment, unlimited email verifications, and complete ownership of databases. However, there are quite a few cons to software email verifiers: update installment, need for backups (i.e. no automatic cloud storage), access limited to a single device, as well as PC and OS requirements, plus no integrations. If this sounds like a dated solution, you may want to look into SaaS options.

SaaS (software as a service) email checkers, like, offer a cloud-based system that lets you work right from the browser with all the data saved in the cloud and all the processing performed there. SaaS solutions usually use a subscription model with monthly limits on email verifications, but they always offer a variety of plans to fit any budget, as well as freemiums. 

Such model is also perfect for those who don’t need to test emails all the time and are looking for a pay-as-you-go or one-time solution. Among other advantages are an unlimited access to your account and database from anywhere in the world and any device, team work options, no restrictions in OS, APIs, and often an all-in-one toolbox offered within one subscription (for example, an email verifier offered by comes as a part of the email finder/verifier/sender/tracker bundle, all offered within a single plan, free or paid). 

It’s important to note that both types usually offer single email verification and bulk email verification. If in your research you can’t seem to find a form of an email verifier that suits you, it’s a good idea to actually contact the verification service of your choice to find out what custom options they offer.

How to choose an email verifier

It’s always easy to choose between two options. But the market offers dozens of tools and that’s where the task becomes complicated. Here are some tips on how to choose the best email tester.

1. Price per 10,000 email verifications
You might think,“The more you pay, the more you get”, but this is not always the case. Despite often offering the same level of service, the prices set by tools can vary from $69 to $2000 per 10,000 verifications. Try to find the sweet spot to get the most out of the platform at the most suitable price. This email verification services comparison page might be of help.

2. Freemium
If you need an email verifier for an occasional email validity check or you’ve just started an email list of under 100 leads, you may want to look into which services offer freemiums. While tools like offer 100 free email verifications per month, services like RocketReach and Neverbounce only offer 3 checks per month, or 20 email verifications with Anymail Finder. 

3. Verification methods
Not all platforms open up about the details of how the verification process is conducted. But you may want to do your research to be sure that the results provided are accurate. As we’ve mentioned before, our own tool uses a 7-step email verification process. However, regardless of the service you choose, make sure it uses SMTP Authentication (aka email ping) for the most accurate results.

4. Extra tools and features
In 2020, not using tool bundles is a waste of time and effort. Why switch between a dozen tools when you can have them all on a single platform? Fortunately, many email verification services offer complete tool boxes with email finders, verifiers, senders and trackers. We’re one of them!

5. API verification
If you want to incorporate email verification directly into your platform or product, you’re going to need an API. This isn’t exactly a must-have for every email verification platform, but it opens up possibilities for email verification in ways you probably haven’t considered before.

6. Integrations
Email verification is just one of the steps in organizing your email marketing and sales. And it’s likely that most of your sales and marketing efforts are actually managed through CRMs and other management platforms. To make the synchronization between platforms easy, it’s important to choose an email checker that can be integrated with CRMs like Pipedrive and platforms like Zapier to sync with over 1500 apps, from CRMs to automation platforms, to calendars, etc.

7. Support
Working with complex email marketing tools is no walk in the park, and sometimes you will have questions. That’s why support (preferably human, 24/7 support) is an important element of every great email verification service. Make sure the tool of your choice offers at least two ways to contact the team if you face any issues or have any questions.

8. Reviews
And finally, REVIEWS. You can never truly be sure in the tool until you check real reviews. We recommend looking at platforms like G2 and Capterra which offer instant comparison to competitors as well as deep insights from real users. 

Why choose Email Verifier

At this point, I believe we deserve a bit of outright self-promo. 

We practice what we preach, meaning always works to stay the best email verification service on the market, offering additional verification steps, working on new integrations and API methods, and keeping the prices affordable for any business.

Understandably, you may want to compare us to other options on the market. For this, we once again recommend checking out the reviews on Capterra and G2, as well as using this table where you can compare leading email verification services currently available on the market.

Sign up now to receive 100 free email verifications per month. Join 300,000 users already enjoying reduced bounce rates, improved deliverability, and high sender reputation.

Already a user? Find detailed guides on all tools and features in our Knowledgebase

How to verify email addresses

Whether you need to verify one email, check select emails from your list, or thousands of emails in bulk, you can use email verifiers to do it faster. We’ll show you the easiest ways to do this using

Before we begin, sign up for free (no credit card required) to perform these checks:
(Click to skip)

Individual email verification

On your homepage with Prospects, you will see a Verify email button.

how to verify individual emails

It opens a window where you can type in any email for verification. Once you click Verify emails next to the input field, your email will be added for verification, which should usually take a couple of seconds.

After the verification, you will see one of the three labels (dots) next to the email: red means the email is invalid, yellow indicates unverifiable emails with uncertain status, and green shows valid emails. Every email you’ve added for individual verification can later be found in your lists on the left.

Bulk email list verification

Email verifiers make it easy to verify large email lists in one go – a list of a thousand email leads can be verified in as little as 15 minutes. To start, upload your list of emails to the app by clicking Import From File:

Once you select the file (in Excel, CSV or TXT format) and upload it, it will show up in your email lists on the left. To verify the uploaded list, find and click the purple Verify current list button. 

Depending on the size of your list, the verification may take anywhere from a minute to a couple of hours (with lists of over 10,000 emails). You can later filter your emails by their verification status using the filter in the upper right corner of the list:

email verification statuses

Select email verification

If you don’t want to spend credits verifying every single email on your list of uploaded or collected emails, you can verify selected emails. 

First, check the emails that you want verified from the list. Next, click the double-check button to start the verification.

select email verification

Once the verification is complete, you will see the verification statuses of the emails you selected.

What’s next? Lead enrichment

As you can see, email verification is only hard in theory. That’s why you should trust the email verification services that already have it all figured out!

By investing in an email verifier you will always be sure that the emails in your list are real, valid, and able to accept any email you send to them. This will maintain your bounce rate low, your email sender reputation high, and your deliverability as high as 98%.

What’s next? Why not enrich your leads to improve your personalization and grow sales.

Good luck!

Have any questions about email verification we haven’t covered in this article? Let us know in the comments below and we will add any info we’ve missed with credit to you!

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