How to Clean a List That Fails a Health Check

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A list will be blocked by Klaviyo's abuse prevention system if it contains known spam traps or a high percentage of “bad” email addresses. If your list fails a health check, you will need to take measures to ensure that you remove these addresses and practice good sending habits going forward. If you find either type of email address on your list, take a close look at how you acquired this list and review our Terms of Service.

Spam Traps and "Bad" Email Addresses

A spam trap is an email address seeded onto the internet by inbox and blocklist providers to catch malicious senders. A spam trap will look like a real email address, but won't actually belong to anyone. This means a spam trap will never subscribe, or opt-in, to any lists. This is where the "trap" comes in: if you end up with spam traps on your list then it is because you're either scraping the web for emails, purchasing lists, or otherwise failing to practice good list hygiene.

"Bad” email addresses are either fake email addresses or email addresses with suspicious subscription activity. These are addresses that don’t open emails or are almost guaranteed to mark emails as spam or unsubscribe.

Spam traps and "bad" email addresses don’t open emails, so a sure way to filter these addresses out is to engage in regular list cleaning and remove recipients who you keep sending to but they never open.

Remove “Bad” Email Addresses From Your List

The best and most clear cut way to prevent your list from being blocked is to create a segment of the blocked list that includes engagement criteria.

Create a Segment from a List

To create an engaged segment from a list, create a new segment with the following criteria:

Is in [name of list]


Has received at least one email in the last 120 days


Has opened an email at least once in the last 120 days


Has clicked an email at least once in the last 120 days


This segment will only include people on your list who have opened or clicked an email in the last 4 months. You can tweak the timing thresholds, but do not choose a time period greater than 180 days. Inbox providers penalize senders when they observe a high percentage of recipients have been received emails for the last 6 months but have not engaged within this 6 month period.

Create an Engaged Segment from an Existing Segment

To create an engaged segment from a segment, click on the Manage Segment dropdown in the top right corner of the segment you'd like to refine, and select Clone Segment.


Here, you will be able to add additional criteria or refine the existing criteria. For example, you may want to tighten engagement by adding the following conditions to the cloned segment:


This will create a new segment that only includes people from your original segment who have opened or clicked an email in the last 2 months. You can tweak the timing thresholds but, again, do not choose a time period greater than 180 days. Inbox providers penalize customers who have received emails and have not engaged within 6 months.

A Smart Strategy for Quality Performance

In general, a smart way to run your email marketing program is to have a Welcome Series flow that will send a few emails to people who newly subscribe.

Why is this important?

  • A Welcomes Series demonstrates to subscribers that you are interested in building a relationship with them. It also gives them the opportunity to solidify their relationship with you by engaging with your emails.
  • Once new a subscriber opens an email, they will immediately be included in segments that have engagement criteria.

Your Welcome Series should have at least 2 messages in it, and these messages should be sent within 3 days of a new subscriber opting in. After this series completes, two additional sending practices become important:

  • Don't stop at a Welcome Series— automate other personalized and targeted flows with your subscribers and customers based on other behaviors, such as website and ecommerce store activity. Check out of Flow Library for more ideas.
  • Build your regular campaign sending strategy around segmentation, so you can cater your content to groups of recipients based on what you know about them.

Focusing on the above will keep your lists clean and strengthen your click rates, open rates, and owned revenue. This will also weed out spam traps and other suspicious emails that would otherwise remain in your list despite never engaging with your business.

If you upload a list of profiles, make sure that these are all opted-in subscribers. If they are, you should have strong open and click rates, and recipients that engage will appear in engaged segments. If you focus on adding engaged subscribers and nurturing your relationship with them, your performance and revenue are destined to improve over time and you won't run into issues with poor list health.

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