DemiEmail

GUIDE

Mailchimp to Klaviyo migration checklist

What Klaviyo's Mailchimp integration carries over, what it leaves behind, and the order to switch forms, flows and suppressions without double-sending.

By · Updated · Last verified

Klaviyo's built-in Mailchimp integration carries over your contacts, unsubscribes, cleaned contacts, audiences, recent engagement and Mailchimp ratings, but not your tags, templates, forms or automations (Klaviyo's Mailchimp migration guide). Connect your store first, then Mailchimp, check that suppressions came across, rebuild forms and automations in Klaviyo, test, and only then remove the integration and retire Mailchimp.

Before you connect anything

  • Disconnect Mailchimp from Shopify first. If Mailchimp is integrated with your Shopify store and Shopify is already integrated with Klaviyo, Klaviyo tells you to disconnect Mailchimp from Shopify before integrating Mailchimp with Klaviyo. Otherwise double opt-in emails could go to your existing subscriber list.
  • Connect your ecommerce platform before the contacts. Integrating your ecommerce platform is the first of Klaviyo's four migration steps. Klaviyo's Academy lesson on migrating data adds a check before you move on: confirm data is actually flowing by looking for events under Analytics > Metrics.
  • Use a dedicated Mailchimp API key. Klaviyo recommends creating a new key just for the integration, although an existing key also works.
  • Turn off flows triggered by the list you are importing, unless you want them to send to every imported contact.
  • Know who can export. In Mailchimp, only Owners and Admins can export audiences, and you will need exports for the gaps covered below.

Klaviyo subscribes contacts according to whether they were subscribed in Mailchimp, unless the profile already exists in Klaviyo. Here is how each Mailchimp status is handled:

Mailchimp status What happens in Klaviyo
Subscribed Subscribed, unless the profile already exists, in which case the more recent consent status wins
Unsubscribed Synced straight to the suppression list (Klaviyo's list migration guide)
Cleaned: hard bounced or repeatedly soft bounced, and treated as invalid (Mailchimp) Added to the suppression list
Non-subscribed: gave an email address or phone number but hasn't opted in to marketing (Mailchimp) Not subscribed, since Klaviyo subscribes contacts based on whether they were subscribed in Mailchimp

Four exceptions need your attention:

  • Profiles already active in Klaviyo. If a profile was active in Klaviyo before you added the integration and was cleaned or bounced in Mailchimp, it won't be suppressed in Klaviyo. Export those contacts from Mailchimp as a CSV and upload them to your Klaviyo suppression list.
  • Suppression is global. Someone suppressed in any Mailchimp list is suppressed across Klaviyo, and Klaviyo recommends keeping one main email list.
  • 1-star contacts. Klaviyo's sending domain migration guide recommends also suppressing contacts with a 1-star Mailchimp rating, because sending to them can harm your deliverability. The same guide recommends bringing in all the permission data your previous provider holds, including the subscription method and timestamp for email and SMS opt-ins, plus all unsubscribe and bounce data.
  • Implicit consent. For profiles that never subscribed to marketing, or only gave implicit consent, the Academy lesson recommends contacting your legal team before you email them.

When you upload a suppression file, keep it to a single column with one email address per row. Klaviyo rejects the entire import if the file has any other columns.

What the integration does not bring over

  • Tags. Klaviyo's Mailchimp integration does not sync any tags. Export them from Mailchimp and import them into Klaviyo as custom properties.
  • Most contact fields. Only names, email addresses, Mailchimp ratings and locations sync.
  • Whole campaigns. Klaviyo syncs open and click data, not the campaigns, and only for campaigns with "Sent" status from the last 90 days, excluding A/B tests.
  • Ratings for partial syncs. If you sync only some audiences, ratings don't sync, even for the synced contacts.
  • Deletions. A contact you delete in Mailchimp after connecting the integration is not deleted in Klaviyo.

Plan your exports around this. A Mailchimp contact export can cover an audience, segment, tag or group, can come as separate CSV files per status, and leaves out email report data such as open and click rates. Exports stay in your account for 30 days.

Templates, forms and automations are rebuilt

  • Templates. You can export email templates from Mailchimp and import them into Klaviyo by editing their raw HTML. Klaviyo won't accept a non-transactional HTML template without unsubscribe tags, and after import you edit that template's HTML directly.
  • Forms. Mailchimp forms can't be redirected to Klaviyo. Replace every sign-up form and list growth tool, and remember that all Klaviyo lists are double opt-in by default.
  • Automations. Klaviyo calls automations flows. Recreate each one as a flow.
  • Imported dates. The Academy lesson notes that values such as Last opened need the format YYYY-MM-DD HH:MM:SS, and that a missing timestamp defaults to midnight UTC, which can throw off date-triggered flows.

Cut over in this order, then test

  1. Point every sign-up form and list growth tool at Klaviyo (Klaviyo's sunset steps). Wait a few days and watch your Mailchimp audiences: new subscribers still arriving means a form still needs swapping.
  2. Put your Klaviyo flows live, then turn off every Mailchimp automation so nobody gets emailed twice.
  3. Test before removing the integration: enter a test email in your sign-up forms, abandon a cart, and sign up for your newsletter to trigger the welcome series.
  4. Remove the Mailchimp integration. Audiences and profiles already synced stay in Klaviyo.
  5. Only then clean contacts in Mailchimp. Cleaning them while the integration is still connected suppresses them in Klaviyo.

Sending domain and deliverability

When you migrate your sending domain to Klaviyo, the domain's sender reputation carries over, and deliverability issues will not resolve on their own by switching (Klaviyo's sending domain migration guide). New Klaviyo accounts, and domains registered less than 30 days ago, should plan to warm their sending infrastructure.

Keep your old provider's DNS records until you are finished with it: once they are removed, email stops sending from your branded domain on that platform. For the records Klaviyo itself needs, see DemiSignal's Klaviyo SPF, DKIM and DMARC guide: Klaviyo generates up to 3 CNAME or 4 NS records for authentication plus one TXT record for verification, and DMARC is set up with your DNS provider, outside Klaviyo. If you suspect a deliverability problem before you move, start with the deliverability audit checklist.

Sources

Questions

Does Klaviyo's Mailchimp integration move my automations?

No. Klaviyo calls automations flows, and you recreate them as flows in Klaviyo before turning off the Mailchimp automations.

Will people who unsubscribed in Mailchimp stay suppressed in Klaviyo?

Synced unsubscribes go to Klaviyo's suppression list, but a profile that was already active in Klaviyo and was cleaned or bounced in Mailchimp is not suppressed until you upload it to the suppression list yourself.

Is my Mailchimp campaign history kept?

Not the campaigns themselves. Klaviyo syncs open and click data for campaigns sent in the last 90 days, excluding A/B test campaigns.

LET'S FIND THE NEXT STEP

What's happening
with your email?

Tell us what's happening with your email. A person reads your enquiry and replies by email, with questions or with what a scoped piece of work would involve.

Describe your problem