What is Contact List Verification? + Tips and Tools

Jun 7, 2024

Data is pivotal for businesses, but its value is often crippled by poor quality. 

contact list verification - cover photo

Inaccurate customer and prospect information serves as a tax on growth. That’s why contact list verification is so vital.

In this guide, we’ll explore strategies for verifying and cleansing your contact lists at scale.

Don’t let an unhygienic list derail your email performance. Read on to master contact list verification.

What is contact list verification?

Contact list verification checks the accuracy of email addresses in a contact list. It’s usually done through an email verification service like Bouncer. Here’s what the process typically involves:

First, all of the emails are syntax-checked to make sure they are formatted correctly. This checks for things like missing “@” symbols or invalid characters. 

After that, the tool checks the email’s domain to make sure it is active and exists. Any email sent to a defunct domain will be marked as invalid. You want to avoid that.

To verify the email address without actually sending an email, the tool will do a mailbox check, which involves pinging the email server to determine if the mailbox is there. 

It also detects spam traps, which are addresses set up to catch spammers, and removes them to prevent blacklisting. Disposable email addresses, often used temporarily, are also flagged as they can harm email campaign effectiveness.

The tool then makes a list of valid email addresses by filtering out suspicious or invalid ones. You’re left with a clean email list, ready for outreach.

Why is contact list verification necessary?

Did you know that, according to Gartner, the average company loses $12.9 million annually due to inaccurate data? That’s why verifying data is key. But that’s not all. 

See more reasons why contact list verification is essential:

Better email marketing ROI

First, and most importantly, a cleaner list provides a better return on investment for your email marketing campaigns.

Valid email addresses mean your messages reach real people, which boosts open rates and conversions. When your emails land in the right inboxes, people read them and take action. More actions mean more sales and engagement.

Improved domain reputation

Next, a verified list helps improve your domain reputation.

Email providers track bounce rates. High bounce rates signal that your list is full of invalid addresses, which can lead to your domain being flagged or blacklisted

With a clean list, you avoid this problem. Your emails get delivered, and your reputation stays intact.

More engagement

Higher email engagement is another benefit. Valid contacts are more likely to engage with your emails. They open, read, and click through your content, which keeps your audience interested and responsive. When engagement is high, your email metrics improve. This shows your efforts are paying off.

Fewer spam complaints

Lower spam complaints also come from a verified list. Risky or invalid email addresses can lead to spam complaints. Spam traps and inactive accounts harm your sender reputation. 

When you remove these, you reduce the chance of being marked as spam, which keeps your emails in the inbox, not the spam folder.

Better customer experience

Cleaner lists lead to improved customer experience. When emails reach the right people, they find your content relevant and useful, which builds trust and loyalty. People appreciate content that matters to them. A positive experience leads to repeat business and referrals.

Higher quality data

Data quality is super important. Regular verification keeps your contact list current and accurate. Verified contact lists enable standardized data entry formats, which helps in making better decisions. You know who your audience is and can tailor your messages accordingly. Accurate data leads to effective marketing strategies.

In summary, contact list verification is necessary for any serious email marketer. The process is super straightforward, but the benefits are immense. Cleaner lists, better engagement, and improved sender reputation all stem from this simple step.

How to do contact list verification

There are several ways to verify contact lists. We’ll take a look at the three most popular methods: manual verification, programmatic using JavaScript, and using an email verification service.

Option #1: Manually

To manually verify a contact list, follow these steps:

  1. Check for obvious typos or formatting errors in the email addresses. Look for missing “@” symbols, incorrect domain names, extra spaces, wrong TLDs, etc., and remove any invalid addresses.
  2. Use a search engine or online directory to look up the domain name of each email address. Verify that the domain exists and is active.
  3. For business email addresses, visit the company’s website and look for the email format they use (e.g. [email protected]). Cross-check your list against this format.
  4. For personal email addresses, search for the person’s name on social media or other online profiles. If you find a matching profile, check if the email address listed matches the one in your list.
  5. Send a confirmation email to each address asking the recipient to verify their email. Remove any addresses that bounce or result in a delivery failure notification.

While manual verification is accurate, it can be extremely time-consuming for large lists. For bigger lists, consider using an email verification service or a programmatic approach.

Option #2: Programmatically

You can programmatically verify email addresses using JavaScript by leveraging regular expressions and making HTTP requests to check if the email domain exists. Here’s an example:

bulk email list cleaning with javascript

Here’s how the code works:

  1. The emailRegex regular expression pattern is defined to validate the format of an email address. It checks for a non-empty string before the @ symbol, a non-empty string for the domain name, and a non-empty string for the top-level domain.
  2. The validateEmail function takes an email address as input and uses the emailRegex pattern to test if it matches a valid format. It returns true if the email is valid, and false otherwise.
  3. In the example usage section, an array of email addresses is defined.
  4. The code loops through each email address in the array and calls the validateEmail function with the email address.
  5. It then logs a message to the console indicating whether the email address is valid or invalid based on the result of validateEmail.

This code focuses solely on validating the format of the email address using a regular expression pattern. It does not include any additional checks for the existence of the domain or the deliverability of the email address. JavaScript validation has its limitations, however:

  • It cannot verify if the email address actually exists or is active.
  • It lacks advanced checks, such as verifying whether the email account has a full inbox or checking for disposable email addresses.

For more reliable email verification, we recommend using a dedicated email verification service, which we’ll cover in the next option.

Option #3: Using an email verification tool

Email verification tools are an easy way to validate emails in bulk. Let’s take a look at the process using Bouncer:

#1 Create a Bouncer account and get 100 free verification credits.

Bouncer sign up for the only email verifier

#2 Log in to your dashboard.

Bouncer dashboard shows valid emails

#3 Navigate to “Verify List” and click “Add New List.”

#4 You will be prompted to either copy and paste your email addresses or upload a file.

verify emails and ip addresses

#5 Click “Copy & Paste.” Copy your emails and put them in the field:

bulk email verifier

#6 After a few seconds, you will get your results:

results with such addresses that are invalid

#7 You can download the results and remove invalid email addresses from your list.

missing data

That’s it! Now you have a clean email list.

Top tips for contact list verification

We cannot leave you without some contact list verification best practices.

Verify regularly

The upkeep of a clean and correct contact list requires regular verification. Over time, email lists deteriorate; according to studies, this rate is 2.1% per month. Annually, that’s 22.5%.

Contacts can, therefore, become invalid very quickly, which raises bounce rates and reduces deliverability.

You can find and eliminate these invalid addresses by routinely verifying your list. Emails from you continue to reach actual people this way. 

Plan when you will check your contacts—monthly or quarterly. Being proactive about keeping your list up to date will make your email campaign more effective and help you maintain a good sender reputation.

Monitor for spam traps

Protecting your sender reputation requires constant spam trap monitoring. Spam traps are email addresses that are set up to catch spammers. Hitting just one will drastically lower inbox placement rates.

Detect and remove these traps from your list with verification tools like Bouncer. You run less of a chance of having your emails classified as spam when Bouncer can recognize and flag these dubious addresses. 

Your emails will be better delivered and will not wind up in spam folders if you routinely check for spam traps.

Use verification on opt-in forms

Cleaning up your contact list requires email verification on your opt-in forms. You can lower the chance of fake or wrongly entered emails by verifying that new members enter real email addresses on opt-in.

Bouncer enables real-time verification, which catches errors before they reach your database. It instantly marks invalid emails so that your list is filled with only the correct information.

Verification done at the time of entry helps to avoid later problems like high bounce rates and unsatisfactory delivery. Initial list cleanliness increases the efficacy of your email marketing campaigns.

Integrate verification tools with email marketing tools

To make your work easier, connect your email validation services to your email marketing platform. 

Such a smooth integration lets verification happen automatically, which saves you time and work. It keeps your list of contacts up-to-date and correct without you having to check it by hand.

Bouncer works with well-known email marketing tools like GetResponse, Mailchimp, and Moosend. As soon as a new contact comes into your system, these integrations make sure that they are verified

This lowers bounce rates and increases deliverability. You can keep your email list clean and relevant by automating this process.

Clean inactive contacts

Regularly clean out inactive contacts from your list. Email addresses that haven’t engaged in a while may no longer be valid. Inactive contacts can harm your deliverability rates because ISPs view emails that go unopened as less relevant.

Removing these addresses improves your overall engagement rates and guarantees that your messages reach active, interested recipients. Use metrics such as open rates, click-through rates, and engagement frequency to identify inactive contacts. 

Your email campaigns will work better, and you will maintain a better sender reputation if you concentrate on a more involved audience.

Check for role-based emails

Role-based emails like info@, support@, or sales@ are often shared by multiple people, leading to lower engagement. These addresses typically belong to departments rather than individuals, which can reduce the personal connection necessary for successful email marketing.

Use your verification tool to identify these addresses and handle them appropriately. Bouncer and other verification tools can flag role-based emails, which allows you to decide whether to exclude them from specific campaigns or manage them differently.

Top tools for contact list verification

Effective email marketing relies on clean and accurate contact lists. Here are some top tools for bulk email verification, with a focus on their unique features and strengths.


Bouncer for contact list verification

Bouncer is the best email verification service because of how accurate it is and how strong its features are. 

It can verify 99.5% of email addresses accurately, so you know they get to the right people. Real-time verification is a key part of Bouncer that helps you keep your list clean as new contacts are added.

It also includes features like:

  • Syntax validation,
  • Domain validation,
  • MX record detection,
  • Disposable emails detection,
  • Catch-all emails flagging,
  • Deliverability kit.

Bouncer integrates seamlessly with popular email marketing platforms like HubSpot, Constant Contact, and ConvertKit, which makes it easy to automate the verification process.

Additionally, Bouncer offers a deliverability kit to help test inbox placement, verify authentication, and monitor blocklists so that your emails get delivered to the right inboxes.

Bouncer’s global adaptability allows verification of emails from anywhere in the world, and the platform is GDPR compliant, prioritizing data security and privacy.



Zerobounce is known for having a thorough email validation system. It can find invalid, spammy, or abusive email addresses and get rid of them.

The tool has features like email bounce detection, spam trap detection, and abuse email checker. Zerobounce also gives you detailed reports that show you how good (or bad) your email list is. The fact that it works with all the major email marketing platforms makes it a great choice for keeping contact lists clean.



Neverbounce offers a high-speed and accurate email list cleaning service. It can quickly go through a lot of email addresses, and make sure your list is clean before you send out campaigns.

Neverbounce lets you check and process things in real time. It also works with many email deliverability tools, so verification processes are easy and smooth. 

Some of the features include getting rid of duplicate emails, cleaning bulk email lists, and giving a thorough report on the quality of the list.



Verifalia is an email verification service that works in real time and has an easy-to-use interface. It can handle international verification needs and works with email addresses that are written in more than one language.

It also gives detailed reports on each email address, which include an explanation of why the validation failed. The app also has an API that developers can use to add email verification to their own apps. 

Verifalia is a great choice for businesses that want to keep the quality of their data high because it focuses on accuracy and detailed reporting.

Don’t neglect your contact list hygiene

To sum up, verifying contacts is important for keeping an email list that is clean and up to date, which increases deliverability and lowers the risk of spam. 

For small lists, manual verification works. For larger lists, senders should use tools like Bouncer to do more thorough checks than just making sure the format and domain exist.

A verified list is an ongoing process. Regularly clean your contacts, implement double opt-ins, monitor metrics, and comply with data privacy laws. 

If you use the right tips and tools to keep your list clean, you will be able to build better relationships with your subscribers and have more success with email marketing.

So what’s holding you back? Take action to verify your contact list today. The impacts on deliverability and engagement will speak for themselves.

Register for a free Bouncer account and get 100 verification credits!

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