Email list cleaning (The good, the bad and the ugly about email scrubbing)

Isn’t the purpose of email marketing to grow your list and make sure as many people as possible can keep in touch with what you have to say?

Surely, this is true. But it’s not the number you should aim for, it’s the quality of the subscribers.

An email list containing 500,000 subscribers sounds impressive, but if your open rate barely hits 5% with just a couple hundred engaging with your content, then you might as well directly flush your money down the drain.

Over time, your email list engagement will decrease. People will open less number of emails and contact addresses can become inactive and bounce, which is why email scrubbing is an essential part of email marketing.

In this article, we’ll dive into the good, the bad and the ugly when it comes to scrubbing your email list. We’ll teach you not to get fooled by fancy numbers, but rather to focus on building a quality list with subscribers that want to hear from you.

Email list quantity versus quality

You’re collecting new subscribers organically via a signup list. You ask your readers to confirm their subscription using double opt-in. Additionally, you might even use reCAPTCHA to filter out bots. It sounds like you should have a high-quality email list, right?

Yes, but over time the quality of your subscribers will change. Some lose interest and stop opening your messages, or even mark your emails as spam. Others hurt your bounce rate. They can soft bounce because their inbox is full or hard bounce because their email address is not active anymore.

Meanwhile, you keep sending these inactive subscribers your emails. The more inactive subscribers on your email list, the lower your delivery and open rates.

Maintaining the quality of your current subscriber list by regularly cleaning your email list should be as much of a priority as collecting new subscribers.

email list cleaning

Time for a clean-up! Why you should clean your email list

To avoid sending your emails to subscribers that don’t help your business grow, you need to sort out the good ones from the bad ones. When you use an email verification tool, your bounces and unsubscribes will automatically be moved to an inactive list after each sent campaign (at least with MailerLite, that's the case).

It’s important to not just use an email list cleaning service once to scrub your email list, but to do this practice regularly as your list grows. When you actively collect new subscribers, you won't know before sending your new campaign if these email addresses are legitimate.

You can also tell it’s time for a good old scrub when you see your campaign reports and come across trends like:

  • Reduced open rate
  • Lower click-through rate
  • Higher bounce rate
  • More unsubscribes
  • Increased spam complaints
We recommend cleaning your list at least every 6 months.

Why clean your list? When you send emails to inactive accounts or abandoned email addresses, ISPs (Internet Service Providers) like Gmail flag it. These invalid email addresses can also become spamtraps which are very bad for your sender reputation.

What is a spamtrap?

Spamtraps are email addresses used by Email Service Providers (ESPs), ISPs, spamfilter, blacklist providers, etc. to catch bad senders. These addresses are newly created (Pristine) or reactivated using inactive existing ones (Recycled). A third type are email addresses with typos in them (Typos). Spamtrap owners scatter these addresses over the Internet to see what sketchy collectors fall into their "trap" and use or sell these addresses. When a newsletter hits these inboxes, it means the email address wasn't collected legitimately and the list the sender's using might have been bought.

Quickly uploading your list to verify the new subscribers lets you know which addresses earn a spot in your quality, clean subscriber list.

So, how do you clean an email list?

Don’t worry! You don’t actually need to manually check each email address. An email verification service (like MailerCheck) does this for you automatically.

What email list should I scrub?

Ideally, take them all out for a drive to the carwash. But if you have to choose, pick the email list that’s most active and performs best. These subscribers are the ones that drive your email marketing forward, so this is the subscriber list you want to have in its best shape. 

It’s also good to look at old lists if they count towards the total amount of subscribers (and your email service calculates pricing based on this number). Old lists often contain outdated emails.

How to clean your email list with MailerCheck

With MailerCheck, you can verify your email list with a few simple clicks. You just need to provide your subscriber list, we’ll take care of the rest.

After you upload your subscriber list, MailerCheck analyses every single email address for validity.

how mailercheck works

Once the check is finished, the tool exports a clean list that is ready to use.

Wow, now I have fewer subscribers. What are the benefits of email verification?

It’s always hard to see your email list shrink, but once you’re over the initial shock you’ll see that email verification only works in your benefit. Especially because there are so many benefits!

1. ​Reduced cost

By filtering out the contacts that don’t add value to your business, you spend less money sending your email campaigns.

2. Better open and click rates

A smaller but clean email list means better leads. These subscribers want to receive and engage with your newsletter. If you filter out the people that don’t show any interaction, you’ll naturally have better email results.

3. Reduced risk of hurting your sender reputation

Signs of spam, low engagement and many unsubscribes are just a few examples of things that negatively impact your sender reputation (more on that later). A clean email list reduces these risks.

4. Reduced bounce rate

Email verification tools sort out the emails that are likely to bounce. You don’t want these subscribers on your list because it costs money to send them an email, and worse, they will not even receive it.

5. Fewer spam complaints

If you regularly clean your list, you’ll target real subscribers that said yes to receiving your messages. The chances are slim that these people mark your newsletter as spam.

6. More accurate and reliable results

After you eliminate the inactive and fake subscribers, you can work with a list that represents real and qualitative subscribers. This gives you much more accurate engagement metrics. Now if your open rate is bad, you know it’s because the subject line or sender information wasn’t great—not because you targeted spammy or “dead” email addresses.

7. Better ROI

Getting rid of bad subscribers + saving money by only targeting quality leads = better return on investment.


What’s sender reputation?

Internet Service Providers (ISPs) give each email sender a score. The higher the score, the better the chances that the sender's email will be delivered to the recipient's inbox. The lower the score, the more risk there is for the sender of their email ending up in the spam folder or not being delivered at all. A lot of factors influence the sender reputation. Things like spam complaints, spamtraps, unsubscribes, engagement rate, blacklist mentions and the amount of emails the sender sends.

What else can I do to maintain a clean email list?

Apart from regularly cleaning up your list with a tool like MailerCheck, there are a few other ways you can maintain a healthy list.

1. Give subscribers the opportunity to unsubscribe

Don’t cling on your subscribers! We know breakups are tough, but sometimes it’s for the best. Make sure you have an unsubscribe link in the footer section of each email you sent out. If you hide this option it can seriously backfire and result in a spam complaint (or even a SPAMCOP report).

2. Ask inactive subscribers if they still feel the spark

Some subscribers sign up with much enthusiasm but show less and less engagement over time. Inactive subscribers don’t open or click on anything in your letters. Then the question is, do you really need these people on your list if there’s no potential gain? In the grand scheme of things, these inactive subscribers can even damage your sender reputation.

HubSpot’s experiment showed that the amount of engagement subscribers show affects the email deliverability. When you continuously have low open rates, it can result in ISPs treating you as a potential spammer. Getting rid of inactive subscribers will technically leave you with higher open rates and a better sender reputation.

However, this is one theory. Email marketing guru Dela Quist from Alchemy Worx argues that it’s better to keep inactive subscribers. Over time, these subscribers will show signs of engagement again (and potentially even end up converting).

Which leads us to number 3…

3. Run a win-back campaign

The easiest way to find out if there’s still hope for inactive subscribers to become customers, is to ask them directly. A win-back campaign (also reconfirmation campaign) is—as the name implies—meant to win back “dead” subscribers.

When you send a win-back campaign, it’s best to give subscribers a deadline or wait a few days before you take any action. In case you do want to take inactive subscribers off your list: set their status to unsubscribed in your email software. If you delete the subscriber entirely, you can not re-activate them again in case they do react to your email.

Berlin-based period and ovulation tracker Clue does a great job with their win-back campaign (extra kudos for the diversity in their header images).

win back email campaign example
win back email campaign example #2

If a subscriber doesn’t take any action, they receive another email on August 31st (the date mentioned in the newsletter).

win back email campaign example #3
win back email campaign example #4

What about buying email lists? Wouldn’t that much easier to grow my subscriber list…

Let’s get this over with immediately. Nothing good ever came from buying email lists (sorry!).

Imagine if you’d buy your friends, how deep would those relationships be? Probably very shallow, especially after realizing you have little to none in common. You’d probably get annoyed having to spend so much time with these strangers.

The same goes for bought email lists. These people don’t know you, don’t care and most likely get very annoyed when you’re constantly bugging them. When shit really hits the fan, they can even end up suing you (which is totally in their right now that there is the GDPR).

As tempting and easy as it is to buy an email list, don’t. All you’re investing in is potentially hurting your sender (and brand) reputation and contacting leads that will never convert. With that same budget, you can also focus on methods that will actually bring you revenue.

A quality subscriber list: Less is more

Building a high-quality subscriber list is fairly easy when you grow your list organically. The real challenge is to keep your list clean and keep an eye on how your subscribers are behaving. When your email campaign results suffer from low engagement metrics, it’s time to scrub your list. Yes, even though it hurts to see your subscriber list shrink (that’s the bad and ugly for you).

A clean email list will result in better performance, reduced cost and a lower risk of hurting your sender reputation or getting flagged as a spammer (that’s the good! Oh so very good!).