Guide to Migrating from Mailchimp

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Learn how to use Klaviyo’s built-in integration with Mailchimp to streamline the migration process, transitioning all of your Mailchimp data to Klaviyo via a one-time sync.

After you’re completely transitioned to Klaviyo, we recommend you remove your Mailchimp integration.

For a general checklist on how to migrate to Klaviyo from another email service provider (ESP), see our ESP migration guide below.


Migrating from Mailchimp to Klaviyo requires four key steps:

  1. Integrate your ecommerce platform with Klaviyo
  2. Integrate Mailchimp with Klaviyo
  3. Migrate your email templates from Mailchimp to Klaviyo
  4. Sunset your Mailchimp account

Integrate Mailchimp with Klaviyo

Integrating your Mailchimp account with Klaviyo pulls over all of your contact data, including when contacts received, opened, and clicked emails.

Step by step walkthrough of integrating Mailchimp with Klaviyo during the migration

First, you'll need to obtain a Mailchimp API key. We recommend creating a new key specifically for the Klaviyo integration, but you can use an existing key if you would like. You can get your Mailchimp API key by logging into Mailchimp, clicking your account name in the bottom left, then navigating to Account > Extras > API keys.

In Mailchimp account, Extras menu is selected, and mouse is hovering over API Keys

Click Create a Key, then copy the key.

Mailchimp API key highlighted with blurred names to copy to Klaviyo platform integration

Once you've obtained your API key from Mailchimp, go into the Integrations tab of your Klaviyo account. Here, search for Mailchimp on the All Integrations list. Click Add Integration and paste in the Mailchimp API key.

Klaviyo’s Mailchimp integration setup page, with API key from Mailchimp pasted into API key box and first two checkboxes under Advanced Options selected

Once you've pasted in your API key, click to review the Advanced Options:

  • Collect open and click data for MailChimp campaigns - check this option to sync MailChimp engagement.
  • Create Klaviyo lists from MailChimp lists - check this option to sync all your existing MailChimp lists.
  • Only sync specific lists - check this option to only sync specific MailChimp lists. You'll be prompted to choose which lists to sync.

When you review MailChimp documentation, keep in mind that MailChimp sometimes refers to “lists” as “audiences”. A customer’s engagement data in MailChimp is tied to the MailChimp list they were part of when they received a campaign. If you move a customer to a different MailChimp list after they receive a campaign, the engagement data for that customer will not follow the customer to the new list. This means that MailChimp engagement data may not be complete if you switch your customer from their original list to a different list after they’ve received a MailChimp campaign.

If you select Only sync specific lists in Advanced Settings, you'll need to designate all the List IDs to which campaigns were previously sent. Even if a different synced list contains the same contact, if a campaign was not originally sent to that list, you will not see complete engagement data for that campaign.

Klaviyo will only sync campaigns with the "Sent" status. Campaigns with the "Sending" status will not be synced.

After you click Connect to Mailchimp, data will start syncing over within a minute or two.

Sync Frequency

After the first day of establishing an integration, Mailchimp data syncs to Klaviyo as follows:

  • Existing lists sync every 30 minutes.
  • Existing campaigns sync every hour.
  • Every 6 hours Klaviyo checks for new lists and/or campaigns. Once a new list or campaign is identified, they will sync every 30 minutes or 1 hour, respectively.

Review Your Mailchimp Data

Klaviyo pulls in the following data from Mailchimp:

  • When someone received a particular email
  • When someone opened or clicked a particular email (if you checked this integration setting)
  • When someone subscribed to a synced Mailchimp list
  • Emails who have unsubscribed or bounced (these are added to your suppression list in Klaviyo)
  • Existing lists in Mailchimp (or specific lists, depending on what you specified in the integration settings)
  • Contacts' Mailchimp Ratings

If a profile already exists in Klaviyo as an Active Profile before you add the Mailchimp integration, it will not be suppressed if it is suppressed in Mailchimp. For example, if you have a profile who is synced through your ecommerce integration before you add the Mailchimp integration, and this person unsubscribed in Mailchimp, they will not be suppressed in Klaviyo because they already exist as an Active Profile. To suppress these contacts, you can export them from Mailchimp as a CSV and upload them to your suppression list in Klaviyo. Only net-new unsubscribed contacts will be suppressed in Klaviyo with the integration.

Keep in mind that only names and email addresses of contacts will sync; to migrate over custom properties (tags) that may be attached to contact profiles in Mailchimp, see below.

If you delete a contact 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. We receive historical data from Mailchimp from the last 90 days; 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 30 minutes on the first day and checks less frequently as time passes.

Mailchimp metrics are synced from campaigns that took place in the last 90 days. If a campaign is still sending, we will not sync the metrics listed in the following table; 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 within Metrics in your Analytics 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).

When lists are imported from MailChimp (as specified in your integration settings), Klaviyo also syncs a MailChimp Subscribed to List event for each member of the list. This gives you the ability to segment profiles imported from MailChimp according to their MailChimp opt-in timestamp.

Subscribed to List

The Mailchimp Subscribed to List metric indicates when a subscriber opts-in to a MailChimp list. You'll find the MailChimp Subscribed to List metric within Metrics in your Analytics tab. Event metadata includes the MailChimp List Name and the MailChimp List ID. 

Import Mailchimp Tags into Klaviyo

If you use Mailchimp tags to label and organize your contacts, you can manually export and import these tags into Klaviyo. Klaviyo's built-in Mailchimp integration does not sync any of your tags.

Start by navigating to Manage contacts > Tags in Mailchimp to view specific tags you want to sync. Clicking the dropdown next to View will give you the option to "Export as CSV" to export your segment from Mailchimp. Use Mailchimp's guide for more information on exporting contacts with specific tags.

In Mailchimp’s Tags settings, View menu is selected on right-hand side of page for VIP tag, and mouse is hovering near Export as CSV option

Once you've exported your data from Mailchimp you can import it into Klaviyo as custom properties. Custom properties get attached to your Klaviyo profiles, and you can create segments based off of specific properties, or use them to add filters to your flow or dynamically display data inside of your emails.

Migrate Your Email Templates from Mailchimp to Klaviyo

Step by step walkthrough of migrating Mailchimp’s email templates with Klaviyo

Klaviyo has an intuitive drag-and-drop template builder that you can use to recreate your Mailchimp templates. We recommend using this method to build your templates because it will ensure that they are mobile-optimized, responsive, and easy to edit and iterate on going forward.

However, if you don’t have time to dedicate to recreating your Mailchimp templates using Klaviyo’s template builder, it is possible to export your email templates from Mailchimp and import them into Klaviyo.

This process involves editing and updating the raw HTML of the email template. If you would instead like to use Klaviyo’s drag-and-drop editor to recreate your templates, check out our guide to learn the ropes of using Klaviyo’s template editor.

Export Your Template 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.

In Mailchimp’s Templates, Edit menu is selected on right-hand side of page for desired template, with mouse hovering over Export as HTML option

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

Swap Out Template Tags

Klaviyo and Mailchimp use different template tags to insert dynamic content in your emails. For example, the “first name” tag is different in Mailchimp than it is in Klaviyo, so it’s important that you swap out any Mailchimp-specific tags with the corresponding Klaviyo tags.

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

To edit the tags in your template, open the HTML file in a text editor, like Sublime Text. Below is a table of other common Mailchimp tags and their corresponding Klaviyo tags.

Mailchimp Tag

Klaviyo Tag


{% unsubscribe %}


{{ first_name }}


{{ last_name }}


{{ }}


{{ email }}


{% manage_preferences %}


This is the subject line of the email, which is set on a per-email basis in the Klaviyo template editor.


This is the preview text of the email, which is set on a per-email basis in the Klaviyo template editor.

See the Additional Resources below to learn more about Klaviyo's template tags.

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

Import Your Template into Klaviyo

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, check out the article linked below in Additional Resources.

Sunset Your Mailchimp Account

If you begin deleting or cleaning contacts in Mailchimp before removing the integration, these contacts will be suppressed in Klaviyo. Once your Mailchimp account is safely sunsetted, be sure to remove the integration before deleting or cleaning contacts in Mailchimp that you don't want suppressed in Klaviyo. Lists and profiles synced from Mailchimp to Klaviyo will not be removed in Klaviyo if you disable or remove the Mailchimp integration.

After you've moved all your data over to Klaviyo, there are three key steps you can take to ensure that you no longer need your Mailchimp account:

  1. Ensure that your signup forms and list growth tools point to Klaviyo, not Mailchimp
  2. Recreate your automations as flows in Klaviyo
  3. Remove the Mailchimp integration

Signup Forms and List Growth Tools

If you have any signup forms or signup form campaigns in your Mailchimp account, you will want to ensure that these are recreated in Klaviyo so that your list continues to grow in Klaviyo rather than Mailchimp. You will not be able to redirect forms created in Mailchimp to Klaviyo. Instead, you can:

  1. Use the Klaviyo Signup Form Builder to re-create your forms from scratch
  2. Use a third-party list growth tool that integrates with Klaviyo
  3. Integrate your custom form through your ecommerce platform

If you are using a third-party list growth tool instead of Mailchimp's built-in form builder, make sure that this syncs to Klaviyo. Klaviyo integrates with a number of third-party list growth tools. Scan our list of integrations to find the tool that you're using. If you don't see it listed, consider using Klaviyo's native Signup Form Builder to create your forms, or switching to a different third-party tool.

Please note that all Klaviyo lists are double opt-in by default. To change a list to single opt-in, head to that section of our Guide to the Double Opt-in Process.

If you’re using a custom-coded form, there are two ways you can ensure that these contacts sync to Klaviyo. One option is to make sure that your custom form syncs new subscribers directly to your ecommerce platform and that your ecommerce store is integrated with your Klaviyo account. The second option is to point the form directly to your Klaviyo account by updating the Form Action URL. To find the Form Action URL in your Klaviyo account, go to your Lists & Segments tab and click on the list where you want to add your new subscribers. Click on the Subscribe Pages tab and copy the URL from the right side of the screen.

After switching all your signup forms to point to Klaviyo, wait a few days and watch your lists in Mailchimp. If you notice subscribers are still being added to these lists, there's probably at least one form that still needs to be swapped out.

Next, you'll want to turn off your Mailchimp signup forms. To do that, head to the code of the page where you installed the form and remove the code that begins with

<!-- Begin Mailchimp Signup Form -->

and ends with

<!--End mc_embed_signup-->

Email Automations

Klaviyo refers to email automations as flows and allows for much more advanced and targeted sequences. It is important to recreate these in Klaviyo so that you don't need to continue to use Mailchimp to send triggered emails.

As you move from Mailchimp, it may be a good time to refresh and update your automated messaging. The two flows we recommend that you turn live as soon as possible in Klaviyo are your welcome series and abandoned cart flows. A welcome series is particularly important to engage new subscribers, and abandoned cart flows have the highest ROI of any other type of flow.

Once your Klaviyo flows are live, you will want to turn off all of your automations in Mailchimp to ensure that you're not double-emailing people. To do this, click Pause and Edit next to the specific campaign. Then, click Pause in the pop-up.

Turning off Mailchimp automations from Email Campaign page, mouse hovering over Pause and Edit button on right

Remove the Mailchimp Integration

Once you’ve pointed all of your list growth tools to your Klaviyo account, paused your Mailchimp automations, and turned your Klaviyo flows live, you can remove the Mailchimp integration. Before you remove your Mailchimp integration, make sure to double-check that everything is working as expected. Enter a test email into your signup form and other list growth tools, abandon a cart, and sign up for your newsletter to trigger a welcome series. Go to the Profiles tab in your Klaviyo account to make sure that the information in the profile reflects all of the correct communication. If the list you sign up to is double opt-in, be sure to confirm your email first.

Once you've taken these steps and are fully migrated to Klaviyo, you can go ahead and remove your Mailchimp integration. Click on the Integrations tab and select Settings under your Mailchimp integration. Select Remove in the upper right and confirm that you want to remove the integration.

Klaviyo Mailchimp integration screen, with mouse hovering over Remove option in top right-hand corner of the site

Send Your First Campaign with Klaviyo

Once your Klaviyo account is integrated with your store and all of your data is ported over from Mailchimp, you can send your first campaign with Klaviyo. For deliverability reasons, we recommend sending to a highly engaged group of contacts for your first 4 weeks on Klaviyo. This will ensure that you start off on the right foot with Klaviyo and train inbox providers like Gmail, Yahoo, etc. to place your emails in the inbox.

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 send your first campaign, you must first build a segment of engaged subscribers. Klaviyo provides a default Engaged (3 Months) segment that will appear in the Lists & Segments tab. You can use this as a starting point, and then decrease the timeframe to 30 days and add historical Mailchimp engagement criteria to ensure that you’re reaching the right audience.

Showing process of setting up Engaged Segment in Klaviyo’s Segment builder with numerous options

Once you have built this segment, you can go through the steps of creating and sending a campaign.

  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 above 20%, expand the timeframe conditions of this segment and continue to monitor open rates

Remove Non-Engaged Audiences

In addition to sending to engaged subscribers, it’s important to remove or clean out anyone who hasn’t engaged with your campaigns to further protect your sender reputation. As noted above, the Mailchimp to Klaviyo integration automatically migrates the 'Mailchimp Ratings' tag as a profile property in your Klaviyo account. This allows you to create segments in Klaviyo that can be used to identify audiences that could be considered non-engaged (generally a 1 or 2 star rating according to Mailchimp).

Focus on cleaning the users that have a Mailchimp rating of 1 star, as they have most likely unsubscribed or have soft bounced before. We recommend suppressing or deleting these subscribers by following the steps outlined in our Guide to List Cleaning.

Users that have a Mailchimp rating of 2 to 3 stars may either be new subscribers or consistently low-engagement subscribers over a period of time. In these cases, it’s helpful to qualify these subscribers further by reaching out to ask what type of content or cadence they would like to receive from your brand. This way, you can determine if they should be removed from your lists or if they need better targeted and more personalized content. Learn more about these sending best practices in our guide on How to Create Customer Segment Tiers.


The table below is a list of commonly used Mailchimp terms, along with their Klaviyo counterparts.

Mailchimp Term

Klaviyo Term




An automated sequence that is set in motion by a specific trigger and then includes one or more steps. Flows can be built to send emails to recipients, or they can simply apply certain actions; ex. abandoned cart, welcome series, updating a profile property.

Email Campaign


A one-time email send to a list or segment of customers; ex. product launch or sale email.


Custom properties

Custom values that can be added to contacts’ profiles and are available to use in segments and flows; ex. gender, birthday, product interest.

Advanced Segment


A dynamic group of people constrained by a set of conditions. Segments do not need to be based on a particular list; ex. anyone who purchased more than 6 months ago and hasn’t purchased since. Regardless of your subscription plan, you can use this feature to add a large number of different conditions.

Signup Form Campaign

Signup form

An embedded, popup, or flyout email and data collection tool.

Ad Campaign

Facebook Advertising Integration

An integration between Klaviyo and Facebook that allows you to display targeted ads to audiences on Facebook and Instagram.

Cleaned Contacts

Suppressed profiles

Contacts who have unsubscribed, marked an email as spam, hard bounced, or have been manually suppressed. It is not possible to email these contacts.


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

If I unsubscribe someone in Mailchimp, are they unsubscribed in Klaviyo?
No. If someone is suppressed in just one Mailchimp audience, they will be removed from the list in Klaviyo, but will not be suppressed globally in Klaviyo. Contacts who were already synced through another integration (i.e. your ecommerce integration) will not be suppressed even if they have unsubscribed in Mailchimp. To suppress these contacts, you can export them from Mailchimp as a CSV and upload them to your suppression list 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 15 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?

How often does my Mailchimp data sync with Klaviyo?
Your lists will sync every 30 minutes and your unsubscribes, opens, and clicks will sync every 30 minutes on the first day of your integration and will sync less frequently with time as you should be migrated over after your first few days.

Do I need to select an email plan in Klaviyo prior to migrating from Mailchimp?

Do all steps of the migration process need to be completed in one sitting?
No, they can be done one at a time.

How often will my Shopify store orders sync with Klaviyo?
Orders sync with Klaviyo in real time.

How often will my BigCommerce store orders sync with Klaviyo?
Orders sync with Klaviyo in real time.

Does the integration pull all of my campaign history?
Klaviyo syncs the last 90 days of campaign history. This is sufficient data for building a list with good engagement criteria

Why should a company keep Mailchimp and Klaviyo? Why not fully commit to Klaviyo and import everything into it?
We recommend switching over fully to Klaviyo. You can start by integrating with Mailchimp. Next, check out the key guidelines outlined here.

Does Klaviyo offer something similar to the Mailchimp rating?
We do not currently offer something equivalent to a Mailchimp rating. Instead, you can use Klaviyo’s segmentation builder to create an engaged segment that matches your specific definition of engaged.

Additional Resources

Klaviyo Resources


Email Deliverability



Lists and Segments

People and Profiles

Signup Forms


Mailchimp Resources

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