Email Newsletter List Cleaning: the Essential Guide

cell phone screen saying "subscribe" denoting email newsletter list cleaning

Based on most industry benchmarks, the average newsletter open rate is ~20% – meaning that 4 out of every 5 emails aren’t opened.

Seems crazy right?  The vast majority of people you are emailing aren’t going to read your email.

Part of this is natural – I love Patagonia’s emails but I only have time to read probably 50% of them.  It’s kind of like my newspaper and magazine subscriptions –I like being able to scan headlines and stories each day / week, but probably only read 50% of the time.

But for the most part, 80% of people not opening isn’t because people are choosing not to read half of them. For the most part, it’s because a huge portion of the people you email never read your emails – and might not have for years.

It’s time to rethink email marketing. By cleaning your list and being selective about who you email to, you’ll not only stop harassing the never openers, you’ll also help the loyal readers by keeping your emails out of spam folders.

The 5 Reasons List Cleaning Matters

At some point in my past, I gave Costco my email address, and since that day, they’ve faithfully emailed me every 2-3 days.  I have no recollection of when or why I gave them my email address, nor do I recall ever opening one of their emails.

So why does Costco keep sending them to me?  Likely because it’s just easier too – email is cheap and they probably haven’t spent time looking at whether I interact with emails.  The thing is, I actually really like Costco as a company – but the never ending stream of emails are pretty annoying.

Email isn’t as “free” as it appears.  There are 5 reasons list cleaning matters:

  1. It stops the hate.  While Gmail does a good job of filtering out Costco’s emails, it’s still somewhat annoying to me that they fill my Promotions tab, show up on my phone, take time to download, etc. This is largely why email marketing can get a bad name – too many emails that just keep coming even though you never respond.
  2. It increases your deliverability. How recipients interact with emails from your domain (how many they mark as spam, how many they open, etc) and bounces are used to determine whether your emails are classified as spam. So – having lots of uninterested people on your list will only hurt getting your emails to the rest of the customers on the list.
  3. It helps with customer retention. By knowing when people start to fade away, you can start to send targeted campaigns to re-engage them.
  4. It helps with personalization and analytics. By knowing that your list is full of real, active, interested potential customers, you can start to personalize content around those people.
  5. It saves you money. While not the most important reason, most email platforms (Klaviyo included) price based on the number of peoples you email or emails you’re sending. So list cleaning will reduce that total number.

If you Google list cleaning, you’ll also read lots of articles about how your open rates will go up when you clean your list and that’s the reason to do it.  This is a bit deceptive – yes, your open rates will jump, but you still have the same number of openers. Beware: open rates can be liars – they might just be a proxy for how clean your list is.

What’s interesting is that you actually improve overall performance from those openers by increasing how many emails get to them (while also making the never openers happier by stopping emails they don’t read).

Recommended Segmentations for Cleaning your List

To begin cleaning your newsletter list, we recommend segmenting members it in a few ways:

  • New: Customers who joined your mailing list in the last 6 months. They stay regardless of their behavior.
  • Very Active: Customers who open more than 30% of your emails
  • Active: Customers who have opened an email in the last 3 months or made a purchase in the last 6 months
  • Fading Away: Customers who opened emails 4-6 months ago but not since
  • Inactive: Customers who haven’t opened an email or made a purchase

Determining what the time frame is depends on how often you email and how often you expect customers to come back and purchase. While it is dependent on your business, our rough rule of thumb is that if someone hasn’t opened the last 25 emails, they’re unlikely to return.

How to Clean your List

If you’re currently using Klaviyo, you can learn more about how to clean your list with step by step instructions here.

Additionally, there are also list cleaning services that can help as well (particularly if you haven’t been emailing your list as often since then you won’t have as much of the data above on who does and doesn’t open).  Two that Pardot recommends are:

These services take care of opt-outs, bounces, invalid emails, etc. You still won’t be left with a great measure of who the openers vs non-openers are, but they’re a starting point.

What to do when Emails go Bad

So – you’ve identified a set of emails to potentially remove.  A few next steps:

  1. Send a 2-3 email re-engagement campaign.  Email customers and let them know that you’ll be taking them off the list unless they click a link in the email.  This gives customers a final chance to choose to stay on the list, and lets you target an email directly to them encouraging it.
  2. Offer fewer emails. Alternatively, if you’re sending 2+ emails a week, you might want to try offering fewer emails to customers who have started opening less.  Some companies, like Linkedin, have even started automatically migrating customers down to fewer emails.
  3. Remove customers from your list.  Finally, once you’ve tried to bring customers back, simply remove the others from your mailing list.

The amazing thing we see is that even with removing thousands of emails from your list, you’ll generally see zero impact on the $’s/email generated from campaigns – and over time you’ll see them increase.

Cutting-edge email marketers automate this whole process – automatically removing customers from the newsletter when they stop reading emails and feeding them into a re-engagement campaign so the list is always clean.


By not cleaning your email list, you’re likely losing money, missing an opportunity to run smart re-engagement campaigns, and harassing people.  By breaking your customers into smart segmentations and automating the process, you can make sure you always have a clean list.

Do you clean your lists? Do you have emails that have kept coming for years that you don’t know why you get? We’d love your thoughts.

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