Migrate contacts from Mailchimp to Omnisend using our built-in integration. No CSV export required. The integration syncs contacts, tags, segments, and engagement data automatically.
Before You Begin
Omnisend imports the following data from Mailchimp contact lists:
Default fields: First name, Last name, Phone, Address (line 1, City, State, Zip code, Country code). These map to default fields in Omnisend contact profiles.
Contact statuses: Subscribed, Non-subscribed, and Unsubscribed for the Email channel. If a contact was synced from your store with a subscribed status but is unsubscribed in Mailchimp, the Mailchimp sync updates the status in Omnisend. Contact statuses and newly subscribed contacts sync in real-time.
Engagement data: Average open rate and average click rate. These are added as custom properties with the prefix
mailchimp_[stats_name]. The percentages show how often a contact opens or clicks campaigns.Tags: VIP and all other Mailchimp tags sync as contact tags in Omnisend.
Segments: Omnisend adds a tag (
mc_segment_[segment_name]) to every contact for every Mailchimp segment. You can recreate Mailchimp segments in Omnisend using tag filters.Language property: Imported as a custom property named "language" (without the "mailchimp_" prefix).
Other data: Any contact data not listed above (e.g., Birthday, OPTIN_TIME, OPTIN_IP, CONFIRM_TIME, LATITUDE, LONGITUDE, TIMEZONE, LAST_CHANGED, NOTES) is imported as custom properties.
Important Notes:
Birthday date format: Mailchimp uses MM/DD; Omnisend uses YYYY-MM-DD. Birthday dates are imported as custom properties. To use them in Birthday automation workflows, export contacts from Mailchimp, update the date format (add any year), and upload the file manually.
Date-added field: The date a contact was added to Omnisend is set to the import date, not the Mailchimp sign-up date. The Mailchimp sign-up date is transferred as a custom property.
Setup Process
Step 1. Generate an API key in Mailchimp:
Sign in to your Mailchimp account.
Go to API Keys (direct link).
Copy an existing API key or click Create A Key.
💡 See Mailchimp's guide on API key generation for step-by-step instructions.
Step 2. In Omnisend, go to Apps (top right corner).
Step 3. Find the Mailchimp Data Import Tool app and click Connect now.
Step 4. Paste the API key you have generated in MailChimp and click Continue.
Step 5. Choose sync settings (what data you'd like to sync to Omnised):
Audience(s): You can either sync all contacts or sync only selected contacts.
Tags: Choose whether to pass contacts with tags they have in your Mailchimp account.
You can always go back and adjust the selected settings.
💡 All contacts imported through the Mailchimp Data Import Tool receive the tag "source:mailchimp".
Note: If you sync one Audience only, engagement data (open/click rates) syncs from that Audience. If you move a contact to a different Audience in Mailchimp, engagement data stops updating for that contact.
Step 5. Once done, click Connect to Mailchimp.
You'll see a confirmation banner that the tool is connected, and your audience will be continuously synced from Mailchimp to Omnisend.
Step 6. After the integration completes, you can check the sync status and last sync date under Apps → Connected apps.
💡 What Happens After Sync?
Immediate import: All Mailchimp contacts and data are imported as soon as the integration completes.
Real-time sync: Omnisend syncs new contacts and subscription statuses from Mailchimp in real-time.
Daily sync: Tags, names, and other contact properties sync every 24 hours.
⚠️ Important: If you archive, permanently remove, or delete your Mailchimp account, Omnisend unsubscribes all contacts synced from Mailchimp. To prevent this, disable the sync in Omnisend before closing your Mailchimp account: Go to Apps → Connected apps → find MailChimp → click Remove.
Next Steps
After the sync completes, follow these steps to build your sender reputation:
1. Warm up your sending reputation
When migrating from one email service provider (ESP) to another, start by sending campaigns to your most active contacts, then gradually increase your audience size.
Omnisend syncs average open rate and click rate from Mailchimp as custom properties (mailchimp_avg_open_rate and mailchimp_avg_click_rate).
Use these to identify engaged contacts:
Go to Audience → Segments → Create from scratch.
Add filter → Custom Properties →
mailchimp_avg_open_rate→ is more than 20 (less or more based on your sending frequency).Save as "Engaged Contacts."
Send your first campaigns to this segment only and follow the full warm-up plan.
2. Explore communication channels
Reach your customers through their preferred communication channels in Omnisend (Email, SMS, push notifications).
Troubleshooting
Resyncing Contacts from Mailchimp
If you:
Sync contacts from Mailchimp using the integration;
Delete those contacts in Omnisend;
Try to resync the same contacts – they will not resync.
Omnisend records that these contacts were removed, so they're skipped during resync.
To bring them back:
Option 1: Create a new store in Omnisend and reinstall the Mailchimp integration.
Option 2: Export contacts from Mailchimp and import them manually via file upload.
FAQ
How do I recreate my Mailchimp segments in Omnisend?
Mailchimp segments are imported as contact tags with the format mc_segment_[your_segment_name].
To recreate a segment:
Go to Audience → Segments → Create segment → Create from scratch.
Add filter → Tag is → select the tag starting with
mc_segment_.Save the segment.
Repeat for each Mailchimp segment you want to use in Omnisend.
Why did my Mailchimp contacts suddenly sync again after months?
The Mailchimp integration syncs continuously:
Real-time: Subscription status and new contacts.
Every 24 hours: Tags, names, and other properties.
If the integration is still active, contacts may resync if you make changes in Mailchimp. To stop syncing, go to Apps → find Mailchimp → click Remove.
Need help? Contact our 24/7 Support Team via in-app chat or at [email protected].