Email marketing is one of the cornerstones of eCommerce. Building an email list is a crucial step toward building an email marketing strategy, but there's more to it than just collecting as many email addresses as you can. In fact, the quality of your email list is one of the factors that determines how successful your email marketing can be. To create a high-quality email list with the most potential, it's going to require some maintenance: you need to clean your email list.

Whether you're new to email marketing or just want to make sure you're getting the most out of your existing strategy, this article will explain the process. We'll cover the basics of email lists, why and how to clean them, and some examples of tools that can help.


What Is an Email List?

An email list is a marketing mailing list made up of email addresses. A business builds an email list by giving customers and other potential subscribers the option to sign up for email communications. The business can then send marketing emails to the list on a regular basis. These marketing emails can be newsletters, notifications of upcoming sales or new products, or other promotional material.

Email marketing offers a very high ROI (Return on Investment) when compared to other marketing methods. Since a good email list is very valuable, businesses often do whatever they can to get customers to sign up — but it's important to give them a choice as to whether or not they receive your email communications. Subscribers must be able to opt in or opt out at will, because unsolicited (and unwanted) emails can get your business into trouble.

The CAN-SPAM Act of 2003 allows the FTC (Federal Trade Commission) to enforce penalties on businesses that don't comply with best practices, including fines of up to $16,000. Thankfully, it isn't hard to comply with the CAN-SPAM Act — the requirements can be found at the linked article, and amount to simple things like including your business's physical address, giving customers a way to unsubscribe, and not using deceptive tactics.

But even if you aren't doing anything illegal, your business can still run into problems with email marketing platforms (like MailChimp), email services (like Gmail), domain registrars, and internet service providers, each of whom has their own way of penalizing spammers. For example, an email sender that frequently gets its emails marked as spam by recipients may start arriving directly in the spam or junk mail folder, even for recipients who want to receive the emails and have never marked them as spam themselves.

Cleaning your email list can help reduce the chances of your emails being unfairly marked as spam. There are also other reasons to clean your email list, and we'll discuss them all below.


Why Do You Need to Clean Your Email List?

Cleaning your email list refers to updating it by:

  • Removing recipients who have opted out
  • Removing recipients who have stopped engaging with you
  • Removing email addresses that no longer work

A clean email list offers the highest ROI because it consists only of active email addresses belonging to subscribers who are actually interested in your business. For best results, you should clean your email list on a regular basis.

So, why does cleaning your email list help protect your reputation among email services and stop you from being considered a spammer?

Firstly, it makes your email marketing safer by ensuring the removal of subscribers who have opted out, since keeping them in your email list could put you out of compliance with the CAN-SPAM Act. Letting people unsubscribe is necessary for both compliance and a good reputation. Just have an unsubscribe link at the bottom of your emails and this part of your email list can clean itself.

Secondly, it saves your business money by removing email addresses that aren't getting you any engagement in return. These can be email addresses that do still work, but belong to subscribers that never click any links in your emails or never even open them. Email marketing platforms charge monthly fees that nearly always determine how many subscribers you can have. So, getting rid of the email addresses that aren't getting you any results can be a good decision. Shortly, we'll discuss a strategy for eliminating these from your list.

Thirdly, it preserves your sender reputation by removing outdated email addresses that don't lead anywhere. Emails sent to a nonexistent address will "bounce" back to you to let you know the address doesn't work. ISPs (Internet Service Providers), email providers, and email marketing services all notice if you're sending a lot of emails to dead addresses and getting a lot of bounces. Since spammers don't pay much attention to their email lists beyond growing them, a high bounce rate makes you look like a spammer — and your sender reputation drops. A low sender reputation harms the deliverability of your emails, which means they're more likely to get automatically sent to the spam folder. Removing these bad addresses keeps you in good standing and makes your emails seem more legitimate. Naturally, ridding your email list of outdated addresses also saves money, since otherwise you're wasting a subscriber slot on a dead inbox.

These are the three ways cleaning your email list will help your business. Take them together, and you'll see how a clean email list will solve common issues with email marketing, like:

  • Getting automatically marked as spam even for subscribers who want to receive your emails
  • Sending emails out to subscribers who never engage
  • Wasting subscriber slots (whether through poor engagement or inactive addresses)
  • A high bounce rate that hurts your sender reputation (leading to the spam problem above)

So, now you know why you should clean your email list. The next question is how to do it.


How to Clean Your Email List

Cleaning your email list is not as hard as it might sound. In fact, depending on the email marketing platform you're using, you may already have built-in tools for handling it automatically. If not, there are other services you can use, which we'll explain shortly.


Allowing Email Subscribers to Unsubscribe

Your first consideration is to make sure it's easy for people to unsubscribe if they so choose. The most common way to do this is to include an "unsubscribe" link at the bottom of your emails. Most email marketing software includes this as part of the templates available for building your emails, usually in the footer. Since the bottom of an email is the most common location for an unsubscribe link, people are used to this and will know where to find it.

Clicking the link should remove the subscriber from your list. Email marketing software like MailChimp and its alternatives handles this automatically. Unless you're still sending your emails out manually (why, when there's so much software available?), letting people unsubscribe is the easiest part of cleaning your email list. You'd have to go out of your way to remove that unsubscribe link, and there's simply no reason to do that.


Removing Subscribers Who Don't Engage

Engagement refers to interactions with the emails you send out. Subscribers who open your emails and click links within them are said to be engaging with your email marketing. The best subscribers do both (and the very best make a purchase after coming to your site from your email), but even just opening your email counts as engagement.

However, some subscribers will just let your emails sit in their inbox forever, and never open them. Or worse, they might be marking your emails as spam instead of bothering to unsubscribe. Either way, removing them from your list is beneficial as you can instead focus on subscribers who are actually engaging with you.

One good way to deal with poor engagement is to ask these subscribers if they want to stay on your list, giving them one more chance to engage. If they don't, you can remove them from the list.

This is called a re-engagement campaign. A common method is to send out an email to un-engaged subscribers letting them know you've noticed they don't seem to be finding your emails useful. Make the subject line something obvious like "Do you want to remain subscribed?" and in the body text, include a link the recipient can click to confirm their subscription.

Subscribers who click this link are telling you they do want to keep receiving your emails — maybe they just haven't had time to look at them, or they don't currently need any of the products you sell. However, they want to remain on your email list and may want to buy something in the future, and you've just given them a way to tell you so.

You can make re-engagement campaigns even more interesting by providing the subscriber with a coupon code that might entice them back to your store. Just make sure the message is clear that they need to confirm whether they want to remain on your email list.

Give the subscriber some time to see the email — maybe a week. If they don't click on the link within that timeframe, remove them from your list and send one more email to let them know you've unsubscribed for them. Remember to include instructions on how to sign up again if they want to, in both your re-engagement email and your final email.

You should always assume subscribers who do not engage with a re-engagement campaign want to unsubscribe. If they don't open the re-engagement email, they may not even be seeing it — which could mean it's going into their spam folder. If this subscriber has marked your emails as spam themselves, the best thing you can do is to stop emailing them.

Some email marketing platforms have automated systems that make it easy to set up a re-engagement campaign. The software itself can determine which subscribers are not engaging, send out the re-engagement emails, and automatically remove the subscriber when appropriate. You'll just need to set this up in the software. Check your current email marketing solution to see if it has this feature, or if you're still looking for one, remember this as you evaluate your options.


Removing Outdated Email Addresses

Removing a dead email address from your list is the easiest of all, no matter how you're doing your email marketing. If you're sending emails out manually, just delete any email address that causes a bounce. If you're using email marketing software, check for an option to automatically delete bounced addresses. Your software may even have this option set by default.

Now we'll cover a few email cleaning services that can take care of these tasks for you.


The Best Email List Cleaning Services

While many email marketing platforms include email list cleaning tools, you can also find separate services to handle it.

One benefit of these services is that you can make sure your email list is clean before you get started on a new email marketing platform. For example, if your business is relatively new and you've just now gained enough subscribers to consider using an email marketing platform, you can get a clean start. The same goes for migrating from one email marketing platform to another.

Another benefit is that many email cleaning services have additional capabilities that may not be found in your email marketing program, such as greylisting verification.

Email greylisting is a process used by mail servers or Message Transfer Agents (MTAs) to help prevent spam. It temporarily rejects a "suspicious" email from arriving at a mailbox. Legitimate SMTP (Simple Mail Transfer Protocol) servers will try again to send the email in about 15 minutes, while spam servers will not. The result of being greylisted is that many spam emails don't make it through (because they usually don't attempt to send more than once) while legitimate emails get through on the second try. The MTA then "remembers" the successful email so the next emails coming from that address don't need to pass through the greylist. Greylisting verification is a function of some email list cleaning services that helps prevent your emails from getting greylisted in the first place.

Now let's take a look at some of the best email list cleaning services.




Pabbly is a great example of a multifunctional email list cleaning service, with a full range of features and affordable pricing. Pabbly promises twice the accuracy, but works more slowly than other email list cleaners. If you want your list cleaning to be as precise as possible, and speed isn't an issue for you, it's worth checking out.

Features: Pabbly's multifaceted approach includes anti-greylisting, domain confirmation (checking email addresses for inactive domain names), and duplicate address removal. It also checks for any spam traps the recipient might be using and helps your emails avoid getting caught in them. If it finds an email address in your list it can't verify automatically, it sends a verification email to check whether the address works — these verification emails aren't traced back to you so any bounces that result won't affect your sender reputation. Pabbly also has a database of email addresses that commonly send out spam complaints, and removes these addresses from your list if any are included, to prevent the owners of those addresses from reporting your emails as spam.

Usage: Pabbly lets you upload your email list in several file formats, and can accept .csv, .xls and .xlsx (Excel spreadsheet formats), and even plain text files (.txt.)

Pricing: Pabbly starts at $5 to verify a list containing up to 1,000 emails. The pricing increases depending on the size of the list, but remains affordable for small businesses considering the number of subscribers a small business might have. For example, verifying 100,000 email addresses only costs $165. Only when you get up into millions of addresses does Pabbly start getting expensive ($2,999 to verify 10 million emails), and small businesses aren't going to need a verification of that size. All prices are a one-time fee.


Email Marker

Email Marker

Email Marker is a great choice for a new or small business or anyone unfamiliar with email list cleaning. It's very easy to use, so it can help you understand how email cleaners work even if you decide to try a different service later. It's an especially good choice if you're still working with a very small email list, because you can validate a list of up to 150 emails at no charge. While not as advanced or effective as Pabbly or other solutions, Email Marker is a great way to get your feet wet — and you may decide to stick with it even longer if you like the results. It also promises a full refund if your cleaned email list produces a bounce rate of over 5%.

Features: Email Marker has spam trap detection, duplicate email address removal, automatic invalid address removal, and other crucial features. However, it lacks greylisting verification.

Usage: Email Marker can accept your email list in file formats including .csv, .xls, .xlsx, and .txt. It also integrates with MailChimp.

Pricing: Email Marker lets you verify up to 150 email addresses for free. Verifying a list of up to 1,000 emails only costs $3, and a list of 100,000 costs $161. Validating 2 million emails costs $999 but for lists larger than that, you'll need to contact them. While it isn't clear on their website, validation is a one-time fee.




MailGet claims to be the most feature-rich email list cleaning service, and indeed it's another great example of one that includes tons of functionality. It's a little cheaper than Pabbly (and works faster if speed is important to you) and a little more expensive than Email Marker for some list sizes, but starts to cost less for larger lists.

Features: MailGet includes greylisting verification, automatic disposable email address removal, spam trap detection, and more. It also integrates with services like Zapier so you can set up additional automation, and you can even integrate it directly with the email signup form on your website (although this requires developer knowledge, and isn't necessary for businesses that just want to verify an existing list of email addresses).

Usage: MailGet accepts uploads of email lists in .csv and .xls formats.

Pricing: MailGet starts at $4 to verify up to 1,000 emails. Pricing increases based on the size of your email list, but like Pabbly, remains affordable for small businesses with a list of 100,000 emails only costing $159 to verify. It can clean a list of 10 million emails for $2,899, and also offers a visible price for cleaning 20 million emails ($4,990) in contrast to Pabbly which requires you to contact them for lists of addresses exceeding 10 million. All these prices are a one-time fee.


Ready to Clean Your Email List?

Cleaning your email list is essential for keeping your subscribers engaged, complying with the CAN-SPAM Act, and protecting your sender reputation.

An email list cleaning tool can be considered an important part of your business's ecosystem, along with your email marketing platform and eCommerce software. Just like these other staples, though, you have to make sure you're using the right one for your business's needs.

There are many more email list cleaners on the market, and during your research you may look at many more than the ones we've discussed in this article. When evaluating a list cleaning tool, look for the following:

  • See what features it has, including greylist verification, duplicate email deletion, and more. Also check if any features work in a unique way, like Pabbly's untraceable verification emails to test addresses it can't immediately verify.
  • Learn what file formats it accepts, so you can use formats you're familiar with. For example, if you only have your email list in plain text format, you'll need to reformat it if the email cleaner requires a .csv file.
  • Look for pricing that fits within your business's budget. Remember you can clean an email list for a one-time fee, but if your list is growing very quickly (congratulations on building up your subscribers so well!) you'll need to clean your list more often. See if the service has a refund policy in case you don't get the best results.

Once you've found the right email list cleaning service for your business, keep in mind that it may only be the right one for right now. As your business grows, you might want to look for a more advanced service or one with lower pricing for larger lists. You can always change to another one for your next cleaning, as you won't be "locked in" to only using one service. However, you might also find the perfect one right away, and decide to stick with it for all your future list cleaning — just keep an open mind!

Now that you understand what email list cleaning is, why you need to do it, and how services can do it for you, you can set out as a much more confident email marketer.