Cleaning your email lists is a must and here are 9 tips to allow you to do it perfectly

Cleaning your email lists is a must and here are 9 tips to allow you to do it perfectly

By Anna Benzaquen
Published: 24/06/2024

You’ve created your email marketing campaign and built a solid list of subscribers to send your content out to but you’ve started noticing that your campaigns aren’t as effective as you had hoped or that you’re seeing higher unsubscribe and bounce rates than before. It’s time to clean your email lists.

Cleaning an email list entails regularly updating those lists by removing fake, duplicate, invalid addresses and unengaged, inactive, or unsubscribed clients. Having these types of emails in your list does not mean you’ve done anything wrong up until this point. It’s been shown that email lists degrade by up to 30% every year. Maintaining good list hygiene increases your marketing campaign’s effectiveness and your reputation in the eyes of both your clients and the ISPs.

Your email list is there to build relationships with your subscribers, increase your brand loyalty, and increase sales. If your list is dirty, it can have the opposite effect.

Knowing when your lists need to be cleaned

So you know that cleaning your lists is important but how do you know when or how frequently to prune? As you watch your email and marketing metrics, it should become fairly obvious once you’re looking for it. Red flags that indicate a cleaning is necessary include:

  • When your open rates drop
  • When your click through rates drop
  • When spam complaints, unsubscribes, and bounces rise

How often a list needs to be cleaned will vary depending mostly on its size. With smaller lists, you may be able to start quarterly and increase frequency as your list grows. But don’t take this as a hard and fast rule. If you see your list needs cleaning more often, you can even increase the frequency to weekly. However, if you have a smaller list that needs frequent cleaning, you may need to implement other solutions like double opt-in strategies and varying content to gauge your subscribers’ interest levels.

Benefits to having good list hygiene

Maintaining good list hygiene will be extremely beneficial to your email marketing campaign. Some of the reasons you should take list cleaning seriously include:

  • Lower bounce rates
  • Lower unsubscribe rates
  • Lower spam complaints
  • Lower costs and increased ROI
  • Higher deliverability
  • Higher open and click rates
  • Higher conversion rates

Lower bounce rates

Bounced emails (emails that fail to reach the sender because their inbox is full, there’s an error in their address, or because the email address is invalid) hurt your sender reputation with ISPs and reduce your deliverability. By catching these types of emails early and removing them from your list, you guard against dings to your reputation and you save money by not sending emails to invalid addresses.

Lower unsubscribe rates

Large email lists inevitably will have subscribers who lose interest over time. If you recognize these unengaged addresses early, you can choose whether you want to attempt a re-engagement campaign, decrease the frequency you send to these subscribers, or clean them from your list entirely before they unsubscribe. Dump them before they dump you.

You may also choose to offer an “opt-down” button alongside the opt-out unsubscribe button. Doing this allows your subscribers to reset their preferences for the type of content they receive from you and may help boost their engagement in the long run.

Lower spam complaints

Every time a subscriber moves your emails to their spam folder, the ISP registers it as a spam complaint and might eventually flag your account as a spammer. This greatly reduces deliverability, engagement, and conversion.

Lower costs and increase ROI

If you are using an Email Service Provider (ESP), you already know that each email you send costs you money. Most ESPs charge by emails sent so all those spammed and bounced emails are costing you more than just lost revenue. By scrubbing these addresses out of your list, you improve your email marketing return on investment (ROI).

Higher deliverability

Deliverability is the process of getting your emails into your subscribers inboxes and it depends heavily on your sender reputation with ISPs. If you have high bounce, spam, and unsubscribe rates, your reputation will take a hit (or three). Having a lower reputation with ISPs (which determine where your emails end up) will mean your emails end up in spam folders more frequently - it’s a vicious circle.

When you clean the detrimental addresses from your email list, you prove to the ISPs that you’re not a spammer and improve your reputation which will in turn improve your deliverability.

Higher open and click rates

Your click and open rates are calculated as a percentage of the total number of emails sent. A well-maintained list means that you have removed the addresses that don’t engage by opening your emails or clicking on your links and weighing down your percentage.

Higher conversion rates

Having a clean list means that your emails are getting into the most engaged inboxes. From there, you can adjust your marketing strategies to turn opens into clicks and clicks into sales, converting your subscribers into customers.

Dangers and costs if you ignore list hygiene

  • High costs and lower ROI
  • High bounce rates
  • High unsubscribe rates
  • High spam complaints
  • Lower sender reputation

High costs and lower ROI

ESPs tend to tier their pricing by the number of emails you’re sending. If you sit back, thinking that your email list will run itself once it’s built, you’ll end up paying for emails sent that will never be received. Not only will your costs go up, but your revenue will also go down. The more spammed and bounced emails, the lower your sender reputation and deliverability, which means your content may not even make it into the inboxes of your engaged subscribers. This will hurt your ROI and conversion rates.

High bounce rates

There are two types of bounced emails: soft and hard. Soft bounces usually mean a temporary problem like a full inbox but hard bounces happen when there is a problem with the email address. You may want to remove either type of bounce to be safe, but hard bounces typically indicate more serious problems that will eventually lead to decreased deliverability if not dealt with.

High unsubscribe rates

While some email churn is inevitable, high unsubscribe rates mean that your subscribers aren’t interested in the content you’re sending them. This happens frequently with bought or rented lists. It’s best to avoid these to make sure you’re reaching people who want to engage with you.

High spam complaints

If you ignore your email lists, you run the risk of not noticing when your subscriber engagement falls. People may lose interest, they may have forgotten they signed up for your list, or they may feel overwhelmed by the number of emails they receive from you, all of which may lead to you being dumped in the spam folder. When spam complaints against a sender rise, email providers like Gmail, Yahoo, and Outlook lower your sender reputation and send you straight to the spam folder more frequently.

Lower sender reputation

All of these risks add up. High bounce, unsubscribe, and spam rates all equal reduced sender reputation with ISPs and email hosts like Gmail, Yahoo, and Outlook. When your reputation is lowered, you begin to look spammy and your deliverability is hurt.

How to scrub your email lists (no sponge or soap required)

So, once you’ve decided to clean up your email lists, how do you actually go about doing it? There are many ways to maintain good list hygiene. Here are our favorites:

  • Don’t use bought or rented lists
  • Check for duplicates
  • Remove unsubscribers
  • Check for typos
  • Check for temporary and junk addresses
  • Use double opt-in strategies
  • Give the option to opt-down
  • Segment your lists
  • Use re-engagement emails

1. Don’t use bought or rented lists

This is the biggest mistake in email marketing campaigns. Bought and rented lists may seem like an easy way to get started, but the people on those lists did not agree to sign-up for your list and are more likely to be uninterested by your content. Sending content to those who don’t want it is the definition of spamming someone and is the fastest way to lower your sender reputation and deliverability. Some of the addresses on these lists may also have been changed or be invalid, leading to higher bounce rates. While it’s more difficult and takes longer, the best way to have a good list is to start with a clean list to begin with.

2. Check for duplicates

Every once in a while, a customer will forget that they have already subscribed to your email list and sign-up again. These duplicates bog down your list and run the risk of the subscriber putting your emails in their spam folder since they are now receiving twice the optimal number of emails. These are one of the easiest types of addresses to scrub from your list.

3. Remove unsubscribers

You should know by now that an easily accessible unsubscribe button is beneficial for everyone. If they can’t find your unsubscribe button or the process is frustrating, they may mark you as spam instead which will hurt your sender reputation and deliverability.

However, if they do decide to unsubscribe, you should respect their decision by being sure to remove them from your list. If they unsubscribe but continue to receive emails from you, you will find yourself on another path that leads directly to their spam folder and the ISPs bad side.

4. Check for typos

Typos are easy to make when typing on a smartphone’s tiny touch keyboard but in your email lists they lead to bounces. Some typos won’t be easy or possible for you to find, for instance, if auto-correct changed someone’s name within their email address, but some typos you can spot. Typos like @gmial, @mgail, @yhoo, or @oulook. Fixing these will save an invalid address that had previously bounced your emails and increase your deliverability. Using a double opt-in can mitigate this problem to a certain extent.

5. Check for invalid, temporary, and junk addresses

There are websites available like and that create temporary addresses for people to use when registering for sites they only intend to use once. These types of emails become invalid after a brief amount of time, usually between one and twenty-four hours. These are usually easy to spot as they look like assigned Wi-Fi passwords:


These types of emails will cause hard bounces and it’s best to remove them from your lists.

6. Use double opt-in strategies

Using a double opt-in strategy makes sure that those who sign up for your emails are doing so knowingly and with genuine interest. It also side-steps the issue of spelling errors mentioned earlier because the subscriber will be made immediately aware of their mistake and need to fix it to complete the sign-up process. The double opt-in is great for ISPs, too, because the subscriber opens and clicks on your first email, signaling to them that you are not spam and should be placed in the inbox accordingly.

7. Give the option to opt-down

It’s good practice to make it easy for subscribers to unsubscribe, or opt-out, when they want to so that they don’t begin to feel frustrated with your emails and they don’t drop you into their spam folders instead, which hurts your sender reputation.

An additional option is to add an “opt-down” button that lets the subscribers adjust their preferences with regard to type and frequency of emails they receive from you. Most subscribers will have signed up with you for a reason but that motivation for them may have gotten lost among the other emails you sent. This option ensures they are receiving only the emails with which they are most likely to engage and keeps them from severing ties entirely.

8. Segment your lists

Segmenting your lists lets you organize your subscribers and decide how to act with each type. Sending relevant emails to each type of subscriber will boost engagement and views of your company. It also lets you spot problems with certain campaigns or subscriber sections more quickly than sifting through gigantic lists. When subscribers drop out of engaged segments, you can more easily decide whether to target them with re-engagement emails or remove them from your lists.

9. Use re-engagement emails

Re-engagement campaigns work best when crafted specifically for the segment of your subscribers who used to open or click but have dropped off the grid recently. You can send “We miss you” emails with promotions just for them. You can also send feedback and preference surveys. This strategy is two-fold: you’ll bring moderately interested subscribers back into the fold and identify the fully unengaged subscribers who need to be scrubbed.


Email list cleansing increases your chances of success by deleting addresses that are no longer useful to your organization. Consider gaining marketing health rather than losing addresses. The game is played by removing emails from your list and adding new ones.

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