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The Importance of Email List Verification

Email verification might seem like an unnecessary step, but it's actually crucial for sustaining a successful email marketing campaign. Not only does it help improve deliverability rates, but it also ensures that your data is clean and accurate.
Updated October 3, 2022

You've spent hours crafting the perfect email campaign. The subject line is snappy, the copy is engaging, and the CTA is impossible to resist. You hit "send" with a satisfied grin...only to have your hopes dashed when you realize that half of the addresses on your list are invalid. bounces galore. So much for that campaign.

If this sounds familiar, you're not alone. According to Return Path, an average of 21% of all emails sent are undeliverable. That number goes up to 30% for marketing emails. Ouch. Email verification is a crucial step in any email marketing campaign, yet so many marketers skip it altogether. Don't be one of them! In this blog post, we'll tell you everything you need to know about email verification and why it's so important.

When you send an email, there are three possible outcomes: 1) it goes into the recipient's inbox; 2) it goes into their spam folder; or 3) it gets bounced back entirely. Obviously, you want your emails to end up in people's inboxes so they can actually see them—but that's not always easy to do. In fact, according to data from Litmus, the global email deliverability rate is just over 80%. That means that for every 10 emails you send, two of them probably won't make it to their intended destination. 

There are a number of factors that can affect your email deliverability rate, including things like the subject line, sender name, and whether or not you're using an Email Service Provider (ESP). However, one of the most important things to keep in mind is your "sender reputation." This is basically a measure of how often your emails end up in people's inboxes—and it's something that every ISP takes into account when determining whether or not to deliver your message. 

To put it simply, the better your sender reputation, the more likely your emails are to be delivered. So how do you improve your sender reputation? Here are some tips we wanted to share after years of cold emailing:

Wait, What Is Email Verification?

Email verification is the process of verifying that an email address is valid and deliverable. There are a few different ways to verify an email address, but the most common method is to send a test email to the address in question and then track whether or not it's delivered. 

Several online tools can help you verify large lists of email addresses (we'll get into some of our favorites later), but for smaller lists, you can usually do it manually. Simply test each email address on your list and see which ones come back as undeliverable. If more than 10% of your emails are bouncing, that's a sign that you need to invest in an email verification tool. 

Why Is Email Verification Important? 

There are two main reasons why email verification is so important: deliverability and data quality. Let's take a closer look at each one: 


As we mentioned earlier, anywhere from 21-30% of all emails sent are undeliverable—that's a lot! By verifying your email addresses before you hit "send," you can ensure that your messages are actually reaching their intended recipients. This helps improve your sender reputation, which is one of the main factors that determine whether or not your emails will end up in someone's inbox or spam folder. 

What is an Email Deliverability Rate?

An email deliverability rate is simply the percentage of emails that are successfully delivered to recipients' inboxes. There are several factors that can affect deliverability, including email content, sender reputation, and whether or not recipients have opted in to receive messages from you. 

Why is Email Deliverability Rate Important?

A high deliverability rate is important because it means that more people are seeing your message. If you're sending cold emails, you want as many people as possible to see your message so that you can generate leads and sales. A low deliverability rate can be an indication that something is wrong with your email list or that your messages are getting caught in spam filters. 

How to Improve Your Email Deliverability Rate 

There are a number of things you can do to improve your email deliverability rate, including using a reputable email service provider, keeping your list clean and up-to-date, and avoiding spam triggers in your content. 

1. Use a Dedicated IP Address

Your IP address is like your home address for your email. When you use a shared IP address, you're sharing that address with other senders. This can often lead to ISPs flagging your emails as spam because they see that address is associated with a high volume of emails. To improve your deliverability rate, you should use a dedicated IP address for your email campaigns. This will give you a unique IP address that only you will be using, which will help improve your reputation with ISPs.

2. Keep Your List Clean

One of the quickest ways to get flagged as spam is to have a high number of bounced emails. When an email bounces, it means that it couldn't be delivered to the recipient for some reason (usually because their mailbox is full or the email address is no longer active). A high number of bounced emails tells ISPs that you're not keeping your list clean, which could result in them blocking future emails from reaching their intended destination. To avoid this, regularly remove any bounced or invalid email addresses from your list. You should also make sure to keep an eye out for typos in email addresses (sometimes people accidentally type in .cmo instead of .com, for example). 

3. Monitor Your Sender Score

Your sender score is basically like your credit score for email deliverability. It's a numerical score between 0 and 100 that indicates how likely it is that your emails will be flagged as spam. The higher your sender score, the better chance your emails have of making it into inboxes. You can check your sender score for free. If it's below 90, there are some things you can do to improve it, like using double opt-in for new subscribers and removing any hard bounce addresses from your list (see tip #2). 

Data Quality

It's every digital marketer's worst nightmare: you send out an email campaign to your entire list, and a few days later, you find out that your bounce rate was through the roof. Not only did barely anyone see your email, but now your data is all skewed because of the high number of bounced emails.

Let's say you're running a campaign targeted at recent college graduates. You acquire a list of email addresses from a third-party source and start sending out your emails. But unbeknownst to you, the list is outdated and many of the email addresses are no longer active. As a result, your bounce rate for this campaign is through the roof. 

Not only does this skew your data, but it also wastes valuable time and resources. You could have spent those same resources on a more targeted campaign that would have yielded results. The moral of the story: Always check your data before you make any decisions— otherwise, you might just be spinning your wheels.

A high bounce rate can skew your data and make it difficult to accurately measure the performance of your campaigns. For example, let's say you're trying to track how many people click on a specific CTA in your email. But 10% of the people who receive your email never see that CTA because their addresses were invalid and the message bounced before it ever reached them. As a result, your click-through rate will be artificially low—not great for accurate reporting! By verifying your emails beforehand, you can avoid this issue entirely and get more accurate insights into how your campaigns are performing. 

Accurate Targeting & Personalization

Data quality is so important in an email campaign because it directly affects your ability to accurately target and personalize your messages. If your customer database is full of outdated or inaccurate information, your emails are going to end up in the wrong inboxes—or worse, in people's spam folders. And if your emails aren't properly targeted or personalized, they're going to be ignored. So take the time to clean up your customer data before you launch your next email campaign, and you'll see a major difference in results.


Email verification might seem like an unnecessary step, but it's actually crucial for sustaining a successful email marketing campaign. Not only does it help improve deliverability rates, but it also ensures that your data is clean and accurate. So next time you're preparing to hit "send" on that big campaign, take a few minutes to verify those addresses first—it'll be worth it in the end!

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Written by Justin Gluska
Justin is the founder of Gold Penguin, a business technology blog that helps people start, grow, and scale their business using AI. The world is changing and he believes it's best to make use of the new technology that is starting to change the world. If it can help you make more money or save you time, he'll write about it!
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