Mailchimp to Klaviyo Migration: Moving Without Losing Lists, Flows, or Deliverability

Klaviyo’s Mailchimp integration is a one-way sync with a narrow scope. It brings across four kinds of data (opens in new tab): subscriber information including unsubscribes and cleaned contacts, Mailchimp audiences, email receives, clicks and opens, and Mailchimp ratings. Tags don’t sync, and the campaign engagement it collects covers campaigns sent in the last 90 days.

A Mailchimp to Klaviyo migration that keeps your lists, flows and deliverability intact therefore depends on three things the integration doesn’t handle: the Mailchimp export, the order the steps happen in, and a warming plan for the new account.

We’re a Klaviyo partner, and what follows is the sequence we’d walk a Shopify brand through once the decision to move is made. Mailchimp has its own migration tools and a guide for the reverse move, Klaviyo to Mailchimp.

Mailchimp and Klaviyo organize the same subscribers differently, connect to Shopify differently, and bill on different units.

On data model, Mailchimp stores contacts in audiences and organizes them with tags, groups and segments. Klaviyo stores profiles and organizes them with lists, segments and profile properties. The two vendors recommend the same shape. If you have multiple audiences for a single organization, Mailchimp’s advice is to manage 1 primary audience and use tags to organize contacts (opens in new tab), and Klaviyo recommends that you maintain one main email list in your account (opens in new tab) as a starting point.

On Shopify, Mailchimp’s app connects a single Shopify store to your Mailchimp audience (opens in new tab). The initial sync brings existing customers with their subscription status (opens in new tab). Nine storefront events sync to Mailchimp, from product_viewed to checkout_completed, and five Mailchimp events sync back to Shopify, including email_opened and sms_clicked.

Klaviyo syncs the last 90 days of Shopify data first (opens in new tab), then the complete history, then new data in real time, and we’ve covered how a Klaviyo setup uses that purchase history for repeat revenue separately. There’s also an optional sync from Klaviyo back to Shopify (opens in new tab).

Does Mailchimp still integrate with Shopify? It does. Mailchimp announced a new direct integration on October 26, 2021 (opens in new tab), available that day, and Shopify points merchants to the Mailchimp app (opens in new tab) in the Shopify App Store. Mailchimp and Klaviyo each recommend leaving the marketing checkbox at Shopify checkout unselected by default (opens in new tab).

On billing, Mailchimp charges on contacts stored and Klaviyo charges on active profiles, and the two definitions treat unsubscribed contacts differently.

Mailchimp has also shipped Shopify-specific work in 2026. On June 17, 2026, Mailchimp announced that it now automatically syncs Shopify’s B2B company data (opens in new tab), so wholesale buyers and corporate clients are tagged and segmented without any manual setup. A brand that sells wholesale through Shopify has a reason to weigh that B2B sync before deciding.

The integration connects with a Mailchimp API key and runs one historical sync. When you first integrate Klaviyo and Mailchimp, Klaviyo syncs all your contacts and the last 90 days of campaign data (opens in new tab). That historical sync only occurs once.

After that, existing audiences sync every 30 minutes and new audiences or campaigns sync every 6 hours. The 90 days applies to campaign engagement. Contacts sync in full.

Profile data is limited. Only names, email addresses, Mailchimp ratings and contact locations sync, and Klaviyo’s built-in Mailchimp integration doesn’t sync any of your tags. Whole campaigns don’t come over either. Klaviyo collects Received Email, Opened Email and Clicked Email for campaigns that have finished sending within the last 90 days, and it excludes campaigns that were part of an A/B test.

The install screen has three advanced options, and two of them affect what you can do later. “Collect open and click data for Mailchimp campaigns” brings the engagement history that the warming section below depends on. Limiting the sync to specific audiences has a cost: if you only sync contacts from specific audiences, your Mailchimp ratings won’t sync to Klaviyo, even for those synced contacts.

These integrations are meant for one-time use (opens in new tab), to migrate your contacts into your new Klaviyo account. Everything outside that scope moves by export or gets rebuilt.

Mailchimp has two exports, and they hold different things. With a contact export (opens in new tab), you can export an entire audience, a segment, a tag, or a group, and exports can include subscribed, non-subscribed, unsubscribed, and cleaned contacts. The columns include TAGS, NOTES, MEMBER_RATING, and the consent record: OPTIN_TIME, OPTIN_IP, CONFIRM_TIME and CONFIRM_IP. The contact export is how you keep those opt-in timestamps and IP addresses.

The contact export has limits. Contact exports don’t include email report data, like open and click rates. Signup source and purchase history are among eight things the export leaves out, and contact exports and their CSVs are available in your account for 30 days. Only Owners and Admins can export audiences, and archived contacts export separately from active ones.

The full account export covers what the contact export doesn’t. It has nine categories (opens in new tab), including a Reports folder with open and click data for individual contacts, and a Templates folder with HTML files for all your email templates. Of the two exports, it’s the only one that holds engagement history older than the 90 days Klaviyo syncs. Mailchimp allows 1 account export per 24-hour period, and if you have a lot of data, allow up to 24 hours for the export.

Plan to document automations, signup forms and segment definitions by hand before you start. We’d run both exports before anything is disconnected, and pull these from the Mailchimp account:

The table pairs each Mailchimp concept with where it lands in Klaviyo.

Does Klaviyo import Mailchimp tags? Not through the integration. Export tagged contacts from Mailchimp as a CSV and import them as custom properties, which you can then use in segments, flow filters and dynamic content. In Mailchimp, tags are labels you create to help organize your contacts (opens in new tab).

Groups follow the same route. Mailchimp saves group preferences as audience field data in each subscriber profile (opens in new tab), so they arrive in the contact export as columns, and each column can be imported into Klaviyo as a property. Unsubscribed contacts keep their group designations, so those columns are populated for contacts you won’t be mailing.

Segments are the first full rebuild. Mailchimp lets you export a segment as a static CSV of the contacts in it at that moment, and the conditions that define the segment aren’t part of that file. Write down each segment’s conditions in Mailchimp, then recreate them against Klaviyo’s profile properties and synced metrics. Our guide to building segments in Klaviyo covers the condition types you’ll be rebuilding with.

Automations are the second. Mailchimp calls the feature marketing automation flows (opens in new tab).

Older accounts may also run classic automations. In Klaviyo, all of them get recreated as flows, which means rebuilding each trigger, delay, filter and message. If cart recovery is on the list, our walkthrough of the abandoned cart email flow covers the structure.

Forms can’t be pointed at the new platform. You won’t be able to redirect forms created in Mailchimp to Klaviyo, which leaves three routes: rebuild in Klaviyo’s form builder, switch to a third-party list growth tool with a Klaviyo integration, or connect a custom form through your ecommerce platform.

Can you export Mailchimp templates to Klaviyo? Only some of them. In Mailchimp, you export a template as HTML from its drop-down menu, and that process is only for templates that you’ve custom-coded (opens in new tab). Drag-and-drop templates can’t be exported, so a template built in the drag-and-drop builder won’t export through that menu.

The account export is a second source of HTML. It includes a folder of HTML files for all your email templates, plus the HTML and text content of regular emails you’ve sent.

Imported HTML has two costs in Klaviyo. The first is merge tags: Klaviyo and Mailchimp use different template tags to insert dynamic content in your emails, and Klaviyo publishes an eight-row mapping, including *|UNSUB|* to {% unsubscribe %} and *|FNAME|* to {{ first_name }}. Klaviyo won’t accept a non-transactional HTML template that lacks an unsubscribe tag. The second cost is editing: going forward, you’ll have to directly edit the HTML in order to change the template.

Klaviyo recommends rebuilding templates in its own drag-and-drop builder and offers the HTML route as the alternative for teams short on time. Plan a rebuild, and schedule it against the warming calendar. Google tells senders: “If you change the format of your bulk emails, gradually increase the sending volume of messages with the new format.” (opens in new tab)

Migrating from Mailchimp to Klaviyo requires four key steps: integrating your ecommerce platform, integrating Mailchimp, migrating templates, and sunsetting the Mailchimp account. Three behaviors make the order inside those steps matter.

The first is the Shopify connection. Failing to disconnect your old integration could result in double opt-in emails sending to your existing subscriber list (opens in new tab). Mailchimp’s Shopify connection has to come off before Mailchimp is integrated with Klaviyo, and the prior platform has to be disconnected before Shopify is integrated with Klaviyo. So Mailchimp for Shopify comes off before either Klaviyo integration goes on.

Disconnecting Mailchimp for Shopify (opens in new tab) has two parts: revoke API access in Mailchimp, and then uninstall the app from your Shopify account. When you disconnect, you can choose whether to keep or remove your Shopify data from your Mailchimp account. We’d keep the Shopify data in Mailchimp until every export is finished. Some apps leave code in the theme after uninstalling (opens in new tab), and uninstalling the app from your Shopify admin doesn’t cancel external charges.

Mailchimp’s Shopify connection comes off at the start of the sequence, so identify which of your Mailchimp automations rely on store data and decide what covers them in the meantime. Mailchimp also tells merchants who use its Order Notifications to turn off Shopify’s own notifications to avoid duplicates. If you did that, decide what sends order notifications after the cutover.

The second behavior concerns profiles Klaviyo already holds. If a profile already exists in Klaviyo as an active profile before you add the Mailchimp integration, and it has been cleaned/bounced in Mailchimp, it won’t be suppressed in Klaviyo.

The Shopify integration goes on first, which creates profiles from your Shopify customers before Mailchimp connects. A Shopify customer whose address hard bounced in Mailchimp fits that description. Klaviyo’s fix is to export those contacts from Mailchimp as a CSV and upload them to the suppression list in Klaviyo.

The third is hygiene during the overlap. If you begin cleaning contacts in Mailchimp before removing the integration, those contacts will be suppressed in Klaviyo. That follows from the ongoing sync: existing audiences sync every 30 minutes while the integration is connected, so changes to cleaned status in Mailchimp keep arriving in Klaviyo. Finish list cleanup in Mailchimp before you connect the integration, or wait until after you’ve removed it.

Decide two settings before the import runs. Turn off a live welcome series before importing (opens in new tab) so existing contacts don’t receive welcome messaging. And if you enable Klaviyo’s optional sync to Shopify for all profiles, it covers profiles added through list imports, even if they haven’t interacted with your Shopify store, so the import can create Shopify customer records.

Put together, the sequence we’d follow looks like this:

For the Mailchimp API key (opens in new tab), click your profile icon and choose Profile, then click the Extras drop-down and choose API keys. After forms are swapped, wait a few days and watch the Mailchimp audiences, because new subscribers still arriving there mean a form was missed.

Test before removal: enter a test email into your sign-up form and other list growth tools, abandon a cart, and sign up for your newsletter to trigger a welcome series. Removing the integration doesn’t undo the import. Audiences and profiles synced from Mailchimp to Klaviyo won’t be removed in Klaviyo if you disable or remove the Mailchimp integration.

Unsubscribes have a different scope on each platform. Mailchimp treats all audiences in your account independently (opens in new tab): when a contact unsubscribes from an audience, they opt out of marketing emails and SMS messages for that audience only. In Klaviyo, someone who is suppressed in any Mailchimp list will be globally suppressed.

For an account with several Mailchimp audiences, the numbers will change on arrival. A contact who unsubscribed from one audience and is still subscribed in another arrives in Klaviyo suppressed. Your suppressed count in Klaviyo won’t match the unsubscribed count of any single Mailchimp audience, and your sendable count will be lower than the sum of subscribed contacts across audiences. Reconcile against the combined exports, not against one audience.

Klaviyo records where those suppressions came from. A suppression synced from a provider such as Mailchimp shows the reason User suppressed (opens in new tab). For a profile that already exists in Klaviyo when Mailchimp connects, Klaviyo uses the more recent consent status based on its timestamp.

Double opt-in is set in three separate places. In Klaviyo it’s per list: double opt-in can be set at the list level (opens in new tab), list imports don’t trigger it, and every Klaviyo list starts as double opt-in. In Mailchimp, double opt-in for email contacts can only be enabled for Mailchimp signup forms (opens in new tab). Shopify has its own store-level setting, which requires the Online Store sales channel (opens in new tab).

That default matters for new signups after the cutover. If your Mailchimp forms ran single opt-in, a rebuilt Klaviyo form on a default list adds a confirmation step your subscribers didn’t have before. Decide the setting per list before the new forms go live.

Ratings need care if you use them to choose who gets suppressed. Klaviyo’s advice is that senders moving from Mailchimp should suppress contacts with a 1 star rating (opens in new tab). To determine contact ratings, Mailchimp monitors regular and A/B testing emails only (opens in new tab), and activity from ads, automations, and landing pages isn’t included. The rating reflects campaign activity, so check a contact’s automation engagement in Mailchimp before suppressing on rating alone.

SMS is a separate workstream. Mailchimp’s contact export puts them in a separate SMS folder with fields including acquisition time, revocation time and subscription status. Moving to Klaviyo from another SMS provider (opens in new tab) involves sender setup and number porting, and you should allow up to 4 weeks for the number to port into Klaviyo.

Do you have to warm up Klaviyo after moving from Mailchimp? Klaviyo says yes: “Any new sender must warm up their sending infrastructure when moving to a new email service provider, like Klaviyo.” (opens in new tab) The reason is the shared IPs a new account starts on: Klaviyo automatically assigns shared IP addresses (opens in new tab) to most new accounts.

Your domain’s history comes with you, in both directions. Klaviyo says that when you migrate your sending domain to Klaviyo from a prior ESP, the sender reputation associated with the domain will carry over as well, and it warns that “Deliverability issues will not automatically resolve by switching ESPs.” Klaviyo also says new accounts should plan to warm their sending infrastructure, so an established domain doesn’t exempt a new Klaviyo account.

Google’s guidance on volume changes applies to any platform switch. Google tells senders: “Start with a low sending volume to engaged users, and slowly increase the volume over time.” We cover Google’s, Yahoo’s, Microsoft’s and Apple’s rules in depth in our guide to email deliverability and sender requirements in 2026.

Klaviyo has two processes for a new account on shared IPs, and the Mailchimp integration decides which one you get. Standard warming applies to a new customer who has engagement data or is using a Klaviyo-built integration that syncs open and click events. Platform introduction applies to accounts with only date-based properties, such as last opened, or with no engagement data. Checking the open and click option when you connect Mailchimp is what puts a migration on the standard path, and a CSV-only migration lands on platform introduction.

Standard warming (opens in new tab) applies to marketing branded sending domains and builds on engagement segments at 30, 60, 90, 120 and 180 days. For your first campaign, Klaviyo recommends that you send to fewer than 10,000 recipients. For that first send it suggests aiming for open rates above 30%, using a segment of people who clicked in the last 30 days or subscribed within the last 15.

Klaviyo’s recommended cadence starts with the 30 day engaged segment for the first two weeks. As long as your open rates remain above 20%, you can relax the engagement criteria to 60 days during weeks 3 and 4. After four weeks of sending with at least 20% open rates, you can relax the engagement criteria to 90 days.

If open rates fall below 20%, Klaviyo says to keep sending to the current segment and pause the move to the next one. These are Klaviyo’s thresholds, and Klaviyo warns that Apple Mail Privacy Protection inflates open rates.

The synced Mailchimp data covers campaigns from the last 90 days, so it supports the 30, 60 and 90-day segments. The 120 and 180-day segments need older engagement, which is in the Reports folder of the Mailchimp account export.

Platform introduction uses fixed caps, and it opens up volume over the course of about 30 days (opens in new tab). For daily senders, Klaviyo caps the first four days at 2,000, 4,000, 8,000 and 12,000 subscribers. For one send a week, it runs 2,000, 4,000, 8,000, 14,000, 21,000, 31,500, 47,250 and 65,000 across weeks one through eight.

Klaviyo also has an in-app version called guided warming. It has four prerequisites (opens in new tab), including at least 5,000 active profiles and at least 100 email opens or clicks in the last 30 days, which can be synced from Mailchimp. The feature expires if unused: if you’ve qualified for warming but didn’t send an email in the last 45 days, the warming notifications are dismissed, and once dismissed, guided warming can’t be re-enabled. A long gap between connecting Mailchimp and the first Klaviyo campaign costs you that guidance.

Klaviyo gives two different timings for flows. Its migration steps have you recreate automations and, once your Klaviyo flows are live, turn off all of your automations in Mailchimp so you’re not double-emailing people. Its warming advice is to turn on automations or flows once you’ve created and sent to all your engaged segments, and to only turn on flows that have historically performed well.

Klaviyo defines flows that have performed well with four thresholds: open rates above 40%, click rates above 1%, and unsubscribe and complaint rates each below 0.1%. For flows that haven’t met them, Klaviyo suggests waiting until you’ve sent campaigns from Klaviyo for 2 weeks before turning on the welcome series, 30 days for abandoned cart, and 30 to 60 days for browse abandonment.

That leaves you a sequencing decision for each automation. Pull each one’s rates from the Mailchimp account export and compare them to Klaviyo’s four thresholds. Flows that clear them are candidates to go live in Klaviyo early, and the rest follow Klaviyo’s delayed schedule.

The fixed constraint is that no trigger runs live on both platforms. Mailchimp’s classic abandoned cart and order notification automations (opens in new tab) reach anyone who abandons a cart or places an order in your store, even if they haven’t subscribed to your marketing emails. A cart flow live in both accounts sends two recovery emails to the same shopper.

A new Klaviyo account sends from Klaviyo’s shared domain until you set up your own. Any company is eligible to create a branded sending domain (opens in new tab). For bulk senders, Klaviyo makes it a requirement: “If you are a bulk sender by most inbox providers’ standards, you must set up a branded sending domain to successfully land in inboxes.”

Google defines the term (opens in new tab): “A bulk sender is any email sender that sends close to 5,000 messages or more to personal Gmail accounts within a 24-hour period. Messages sent from the same primary domain count toward the 5,000 limit.”

Google adds “Bulk sender status doesn’t have an expiration date.” Because Google counts by primary domain, a domain that qualified while sending through Mailchimp still qualifies after the move. Yahoo declines to give a figure (opens in new tab): “We will not specify a volume threshold.”

Klaviyo requires up to 3 CNAME or 4 NS records for email authentication (opens in new tab), and one TXT record for domain ownership verification. The NS records belong to the dynamic routing option, which Klaviyo recommends, and the CNAMEs to the static option for DNS providers that don’t support NS records. Ensure that the branded sending subdomain isn’t already being used within your DNS, and pause all sending before activating your first marketing branded sending domain.

Mailchimp’s records are a different set. For Mailchimp to properly authenticate your emails, your domain’s DNS records need 2 CNAME records (for DKIM) and 1 TXT record (for DMARC) (opens in new tab), and you create them as a DKIM record and a DMARC record (opens in new tab). Remove a prior provider’s records once you no longer send there. Sending from that platform on your branded domain stops when they’re gone.

We’d handle Mailchimp’s records in two parts. Remove the two DKIM CNAMEs only after Mailchimp sending has fully stopped. Keep a DMARC record published on the domain throughout, because Mailchimp’s one TXT record is the DMARC record and Google tells bulk senders: “Set up DMARC email authentication for your sending domain. Your DMARC enforcement policy can be set to none.” On both platforms, DNS updates can need as long as 48 hours to take effect.

Both vendors change their prices, and yours depends on your tier, so compare what each platform counts.

Mailchimp bills on stored contacts in tiers, with a send limit tied to the tier. Subscribed, unsubscribed, and non-subscribed contacts (opens in new tab) are included in your contact count, and archived, cleaned, and deleted contacts don’t count toward your contact total or the price of your marketing plan. Going over the contact limit on a monthly plan doesn’t interrupt service. Mailchimp adds a charge instead.

Klaviyo bills on active profiles and emails sent. Klaviyo defines the unit (opens in new tab): “Any profile, regardless of consent status, that can be emailed through Klaviyo is considered an active profile.” Suppressed profiles stay in the account for reporting and leave the billable count once they’re fully processed as suppressed. On sends, Klaviyo charges for any messages that leave the system: any received or bounced emails count toward your plan limit, but skipped emails don’t.

The difference shows up in two groups. Unsubscribed contacts count toward a Mailchimp tier and don’t count in Klaviyo once processed. Never-subscribed contacts, such as Shopify customers who didn’t opt in, count on both platforms as long as Klaviyo can email them.

Klaviyo enforces the match between plan and profile count. Under Klaviyo’s February 18, 2025 billing changes (opens in new tab), “customers will be required to be on an email plan that matches or exceeds their active profile count.” The Mailchimp import and the Shopify sync both add profiles, so the active profile count after those two syncs sets your starting tier. Size the plan from that number, not from your Mailchimp subscribed count.

Reducing the count takes a manual step. Your plan doesn’t automatically downgrade when you reduce profiles, so you must choose a lower tier in the Billing page after your billable profile count has updated. The count can take up to 72 hours to refresh after you suppress or delete profiles. During the overlap, Mailchimp continues to bill on its stored contact count, unsubscribed contacts included.

Klaviyo’s migration wizard isn’t for this move. The wizard is in closed beta (opens in new tab), and it moves existing Klaviyo accounts from Klaviyo’s legacy sending platform to its newer infrastructure. It isn’t for moving to Klaviyo from a different email service provider.

Klaviyo Starter in Shopify is an embedded version of Klaviyo inside the Shopify admin. The app creates (or connects to) a real Klaviyo account (opens in new tab), and some work is only available at klaviyo.com: setting up a dedicated sending domain, browsing and editing profiles, building segments, multi-step automations, and SMS and other channels. The sending domain and segment work covered above is on that klaviyo.com-only list, so run the migration in the full platform.

Mailchimp changed how API keys work. Effective June 22, 2026, any new API key you generate expires 1 year after its creation date. API keys created before June 22, 2026 aren’t affected by this change and won’t expire. Klaviyo recommends creating a new key for the integration, and a key created today falls under the new rule.

Mailchimp gives you two ways to stop: pause or delete. Pausing your account (opens in new tab) stops billing and saves your account data for later use. A pause runs for 3 or 6 months, and Mailchimp limits accounts to 2 pauses every 12 months.

A pause ends without action from you. Your account automatically unpauses and resumes billing (opens in new tab) after the 3 or 6-month period, and you’ll need to reactivate automations after restarting. If you pause as a fallback, put the end date on a calendar and decide before it arrives.

Deletion is permanent. After an account is deleted, it’s permanently closed and can’t be restored, and Mailchimp removes all data associated with audiences, campaign archives, and reports. Confirm that the contact exports, the account export, and your automation and segment notes are stored outside Mailchimp before you delete. The contact export files stay available in the account for 30 days, so download them before you delete.

Once the account is live in Klaviyo, our Klaviyo email marketing agency team offers a free Growth Audit of the account you’ve just built.