Integrate with MailChimp



Klaviyo's MailChimp integration is designed to help you as you move from MailChimp to Klaviyo. We don't recommend using both platforms at once other than during the interim period as you make the switch.

We also have a general checklist that covers how to completely migrate over to Klaviyo from a different email service provider (ESP) here.

Find Your MailChimp API Key

First, you'll need to obtain your MailChimp API key. You can get your MailChimp API key by logging into MailChimp, clicking your account name in the upper left, then navigating to Account > Extras > API keys.


On the API key page, create a new API key and copy it. The field you'll need will be a long string of letters and numbers.


Enable the MailChimp Integration in Klaviyo

Once you've obtained your API key from MailChimp, go into the Integrations tab of your Klaviyo account. Here, find MailChimp on the All Integrations list. Click Add Integration and enter your API key.

Once you've pasted in your API key, review the advanced options.

If you choose Collect open and click data for MailChimp campaigns AND Only sync specific lists, all contacts in your MailChimp account will be imported into Klaviyo. See the section below on Understanding your MailChimp Data for more details.

After you click Connect to MailChimp data will start syncing over within a minute or two. If you click on the Metrics tab in your account, you should see the following MailChimp metrics appear:

  • Received Email
  • Opened Email
  • Clicked Email

The MailChimp Metrics

MailChimp metrics are synced from all previously sent campaigns. If a campaign is still sending, we will not sync the following metics; these metrics will only sync for campaigns that are finished sending.


Clicked Email

The MailChimp Clicked Email metric will track email click events synced from MailChimp. To segment this metric further, and see which contacts clicked which specific URLs in your emails, click on the Clicked Email metric in your Metrics tab and then use the advanced filters option to filter by URL.

Opened Email

The MailChimp Opened Email metric will track email open events synced from MailChimp.

Received Email

Klaviyo will sync a MailChimp Received Email event every time someone successfully receives an email sent from MailChimp (meaning the email was delivered to their inbox).

Understanding Your MailChimp Data

From MailChimp, Klaviyo pulls in the following data:

  • When someone received, opened or clicked a particular email
  • A list of emails who have unsubscribed or bounced
  • Existing lists in MailChimp
  • Contacts' MailChimp Ratings

If you choose to sync existing lists from MailChimp to Klaviyo, you can choose to either sync all of your lists or only specific lists.

If you choose to sync only specific lists AND you enable the option "Collect open and click data for MailChimp campaigns," all contacts in your MailChimp account will be imported into Klaviyo -- regardless of whether or not they're in the specific lists you've chosen to sync. So, while syncing specific lists will recreate them in Klaviyo, it will not necessarily limit the number of contacts imported from MailChimp.

Keep in mind that only names and email addresses will sync; to migrate over custom properties that may be attached to contact profiles in MailChimp, see below.

If you delete people in MailChimp, they will not be deleted in Klaviyo. However, if someone is added to a MailChimp list, they'll be added to Klaviyo within an hour. If you are syncing a large number of contacts from MailChimp, this may differ.  

The integration brings data over every 30 minutes for lists. For campaigns, it pulls data every 15 minutes on the first day and checks less frequently as time passes.

Import Custom Profile Properties into Klaviyo

If you choose to sync existing subscriber lists into Klaviyo through the Klaviyo MailChimp integration, any custom properties attached to these contacts in MailChimp will not automatically flow into Klaviyo.

The one exception to this is contacts' MailChimp Ratings. These will be added to contact profiles automatically as custom properties. See below for more information on MailChimp Ratings.

If you want to preserve and migrate your own custom properties when you switch over to Klaviyo, you will need to manually import them to ensure that the correct properties are appended to their contact profiles in Klaviyo. To do this, follow this guide.

Best Practices

Build an Engaged Segment

Klaviyo pulls in contacts' "MailChimp Ratings," which rate a contact's level of engagement on a scale of 1-5 stars. A contact with 5 stars is considered highly engaged, while a contact with only 1 star is considered unengaged. 

To learn more about how MailChimp Ratings are calculated, check out MailChimp's documentation.

To avoid encountering deliverability issues, segment your contacts from MailChimp based on their MailChimp Rating and previous MailChimp engagement to ensure that you are sending a group of contacts that will open, click, and otherwise engage with your emails. You can do this by building a segment where the conditions are:

If you send weekly or monthly to the segment, lengthen 30 days to 90 days to be more inclusive.

  1. Send exclusively to your "very engaged" segment for 4 weeks.
  2. Monitor your open rates using the Engagement Report.
  3. As your open rate increases, adjust settings on your “very engaged” segment.
    • If you send campaigns daily, you can expand the segment to customers who have clicked or opened an email at least once over the last two months. Then monitor open rates.
    • If you send campaigns weekly or monthly, you can expand to customers who have clicked or opened an email in the last 120 days. Then monitor open rates.

Migrate Email Templates from MailChimp to Klaviyo

If you have spent hours of time designing email templates in MailChimp, recreating them all in Klaviyo may seem daunting. Luckily, it is possible to export your email templates from MailChimp and import them into Klaviyo.

One thing to note about this process, however, is that you will be working with the raw HTML of the template.

First, export your email templates from MailChimp

In your MailChimp account, navigate to the template that you would like to migrate to Klaviyo. In the dropdown beside the name of the template, select Export as HTML


You will be prompted to save an HTML file to your computer.

Before you import your template into Klaviyo, you will have to add an {% unsubscribe %} tag. Klaviyo does not allow you to upload HTML templates that don't have unsubscribe tags unless they're for transactional emails.

To add an unsubscribe tag to your template, open it in a text editor like Sublime. In addition to the unsubscribe tag, you'll also want to switch out any other MailChimp tags with Klaviyo tags.


Once you've swapped out the tags for Klaviyo tags, you can save your HTML file.

Next, in your Klaviyo account, navigate to the Email Templates tab and select Create Template. Then, select Import your Template. Here, you will be prompted to select the HTML file from your computer and you can upload the file you just saved. 


You can see a preview of what your email template will look like in the Preview tab. Please note that going forward, you will have to directly edit the HTML in order to change the template. If you're interested in converting the template to a drag-and-drop template, you can follow these steps.


If I delete people in MailChimp, are they deleted in Klaviyo? 


If I unsubscribe someone in MailChimp, are they unsubscribed in Klaviyo? 

Yes. If someone is suppressed in just one MailChimp list, they will be suppressed globally in Klaviyo.

If I unsubscribe someone in Klaviyo, are they unsubscribed in MailChimp? 


If I add someone to a list in MailChimp, are they added to a list in Klaviyo?

Yes, after 30 minutes if the address has status "subscribed" or "unsubscribed".  If the email address in MailChimp is in status "pending" (added with double-opt in, but has not yet confirmed their subscription) or "cleaned" (the address bounced and was removed from the list), they will not be synced to Klaviyo.  When an address confirms their subscription, they will move from "pending" to "subscribed" in MailChimp and will be synced to Klaviyo in the next periodic sync.

If I add someone to a list in Klaviyo, are they added to a list in MailChimp?

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