This guide walks you through migrating from Mailchimp to Sender, covering subscriber data, templates, automations, and domain setup.
Before You Start
- An active Sender account with a verified email address.
- Admin or Manager-level access to your Mailchimp account (required for exporting audiences and generating API keys).
- A list of what you want to migrate: subscribers, tags/groups, email templates, automations, signup forms, suppression lists, and sending domains.
- A Mailchimp API key if you plan to use Sender's direct import feature (generated under Profile → Extras → API keys in Mailchimp).
- Recommended migration order: domains → subscribers → custom fields → templates → automations → forms → test → deactivate Mailchimp.
Migration Checklist
Subscribers — In Mailchimp, go to Audience → select your audience → Export audience → Export CSV to download your contacts. In Sender, go to Subscribers → Add subscribers and use either Import from a file or Import from Mailchimp (direct API import) to bring your contacts in.
Custom fields — Review the merge fields you use in Mailchimp (such as FNAME, LNAME, BIRTHDAY, or any custom merge tags). In Sender, go to Subscribers → Fields → Create new field to recreate any fields that do not already exist before importing subscribers. Sender includes Email, Phone number, First name, Last name, and Birthday by default.
Tags and groups — Mailchimp uses tags and groups to segment audiences. In Sender, the equivalent is Groups. Go to Subscribers → Groups → Create new group to set up your groups before importing. When importing via CSV, you can assign subscribers to a specific group during the import process.
Email templates — Mailchimp includes template HTML files when you export your account data via Account → Settings → Manage my data → Export Data. In Sender, go to Email campaigns → New campaign → proceed to the Design step and select Custom HTML email to paste your exported HTML code. Alternatively, rebuild your templates using Sender's Drag and drop builder.
Automations — Mailchimp automations (welcome sequences, abandoned cart, win-back flows) cannot be exported and must be recreated. In Sender, go to Automations → Create new workflow and choose from ready-made templates like Welcome, Abandoned cart recovery, Win-back customers, or Onboarding — or select Create from scratch.
Signup forms — Mailchimp signup forms and pop-ups cannot be exported. In Sender, go to Forms → Create a new form and choose between Pop-up or Embedded form types. Recreate your form fields, design, and connected subscriber groups manually.
Suppression lists (unsubscribes and bounces) — In Mailchimp, your audience export includes separate CSV files for subscribed, unsubscribed, non-subscribed, and cleaned contacts. Import unsubscribed and bounced contacts into Sender with their correct status to protect your sender reputation.
Sending domain authentication — In Sender, go to Account settings → Domains → Add domain and configure the SPF, DKIM, and DMARC DNS records Sender provides. Mailchimp's DNS records will not work for Sender — new records must be added to your domain's DNS settings.
Steps to Migrate Subscribers
Step 1 — Export your audience from Mailchimp
In Mailchimp, click Audience in the left navigation. If you have multiple audiences, click the Audience drop-down and select the one you want to export. Click Export audience. In the Export all contacts? pop-up, click Export CSV. Mailchimp will prepare a ZIP file containing separate CSV files for subscribed, unsubscribed, non-subscribed, and cleaned contacts. You will receive an email when the export is ready.
Step 2 — Prepare your file and create custom fields in Sender
Unzip the downloaded file and open the subscribed_contacts.csv in a spreadsheet application. Review the columns — these correspond to Mailchimp merge fields. In Sender, go to Subscribers → Fields and verify that matching fields exist. Click Create new field for any custom data columns (such as company name or address) that are not part of Sender's default fields: Email, Phone number, First name, Last name, and Birthday.
Step 3 — Import subscribers into Sender using a file
In Sender, go to Subscribers → Add subscribers → Import from a file. Drag and drop your CSV file or click Import file to upload it. Supported file types are .csv, .txt, and .xlsx with a maximum size of 64MB. After uploading, map the columns from your file to the corresponding fields in Sender. Select the group to add the subscribers to, then complete the import. Verify the subscriber count matches your exported file.
Step 4 — Alternative: Use Sender's direct Mailchimp import
Instead of a file upload, you can use Sender's built-in Mailchimp integration. In Sender, go to Subscribers → Add subscribers → Import from Mailchimp. To get your API key, go to Mailchimp and click your profile icon → Profile → Extras → API keys → Create A Key → Generate Key → Copy Key to Clipboard. Paste the API key into Sender and click Get lists. Select the audience lists you want to import.
Step 5 — Import your suppression list
Open the unsubscribed_contacts.csv and cleaned_contacts.csv files from your Mailchimp export. Import these into Sender via Subscribers → Add subscribers → Import from a file and ensure contacts are marked with the correct unsubscribed or bounced status. This prevents Sender from sending to contacts who previously opted out and protects your deliverability.
What Cannot Be Migrated
Campaign performance history — Open rates, click rates, send history, and campaign analytics from Mailchimp cannot be transferred to Sender. Export your Mailchimp reports before migrating by going to your profile icon → Account → Settings → Manage my data → Export Data and selecting Reports. Save these files for your records.
Automation analytics — Performance data tied to your Mailchimp automations (such as revenue attributed, conversion rates, and per-email open rates) does not carry over. Note your key metrics from Mailchimp before recreating automations in Sender. New analytics will begin tracking from the first send in Sender.
Form submission history — Historical data about who signed up through specific Mailchimp forms, including submission timestamps and source URLs, cannot be migrated. Sender will begin tracking form submissions from the point you publish new forms.
Mailchimp-specific features — Features unique to Mailchimp, such as Customer Journey Builder maps, postcards, social media ad campaigns, website/landing page builder content, and Content Studio assets, do not have a direct migration path. Evaluate which features have equivalents in Sender and recreate them where applicable.
Email template drag-and-drop designs — Templates built with Mailchimp's visual editor cannot be exported as editable design files. Only the final HTML output is available via account export. You can paste this HTML into Sender's Custom HTML email editor, but interactive editing will require rebuilding the template in Sender's Drag and drop builder.
Post-Migration Verification
Subscriber count — Compare the total number of active subscribers in Sender under Subscribers with the count from your Mailchimp audience export. The numbers should match. Check that unsubscribed and bounced contacts also imported with the correct status under Subscribers → Groups.
Domain authentication — In Sender, go to Account settings → Domains and confirm that your domain shows green checkmarks under Ownership confirmed and Authentication. If records are not verified, click Recheck DNS records after allowing time for DNS propagation (up to 48 hours).
Test email — Create a test campaign in Sender via Email campaigns → New campaign. Send it to an internal email address using Send test email in the design editor. Verify that the email arrives, renders correctly, and that the sender name, reply-to address, and unsubscribe link all function as expected.
Automation triggers — For each automation you recreated in Sender, trigger a test by adding a test subscriber or performing the trigger action (such as joining a group for a welcome sequence). Verify that the automation fires, emails are sent in the correct order, and delays between steps work as configured.
Form rendering — For each form recreated in Sender, preview it on your website or use Sender's built-in preview. Submit a test entry and confirm the subscriber appears in the correct group in Sender with the right field data populated.
Migration Tips
Migrate domains first — Set up and verify your sending domain in Sender under Account settings → Domains before importing subscribers or sending any campaigns. DNS propagation can take up to 48 hours, so starting early avoids delays.
Clean your list during migration — Use the migration as an opportunity to remove inactive or disengaged subscribers. Filter your Mailchimp export to exclude contacts who have not opened or clicked in the last 6–12 months before importing into Sender.
Map Mailchimp merge tags to Sender fields — Mailchimp uses merge tags like *|FNAME|* and *|BIRTHDAY|*, while Sender uses field codes like {{firstname}} and {{birthday}}. After importing, update any merge tags in your email templates to use Sender's field syntax.
Test automations before going live — After recreating automations in Sender, keep them in Draft status and trigger test runs before activating. This ensures triggers, delays, and email content all work as intended without affecting real subscribers.
Keep Mailchimp active during testing — Do not cancel your Mailchimp account until you have fully verified subscribers, domain authentication, templates, automations, and forms in Sender. Run both platforms in parallel during your testing period.
Common Issues
Subscriber count mismatch after import → Mailchimp exports separate files for subscribed, unsubscribed, non-subscribed, and cleaned contacts. If your total in Sender does not match, verify you imported the correct file (subscribed_contacts.csv for active subscribers) and check whether duplicate email addresses were merged during import.
Custom fields not mapping correctly → Column headers in your Mailchimp CSV may not match Sender's default field names. During import, use the field mapping step to manually match each column to the correct Sender field. Create any missing custom fields under Subscribers → Fields before starting the import.
Domain authentication failing → Sender provides specific SPF, DKIM, and DMARC records that are different from Mailchimp's. Ensure you added Sender's records (not Mailchimp's) to your DNS settings. Allow up to 48 hours for propagation and use Recheck DNS records under Account settings → Domains to verify.
Mailchimp merge tags not rendering in Sender → If your imported HTML templates display tags like *|FNAME|* instead of subscriber names, replace them with Sender's field codes (for example, {{firstname}}). Search your HTML for *| to find all Mailchimp merge tags that need updating.
API key not working for direct import → Mailchimp hides previously created API keys. If you cannot find your key, generate a new one under Profile → Extras → API keys → Create A Key. Copy the key immediately after generation — it will not be fully visible again.
FAQs
How long does migration typically take?
This depends on the volume of data and the number of assets to recreate. Subscriber imports take minutes using either file upload or the direct Mailchimp API import. Recreating templates, automations, and forms may take several hours to a few days depending on complexity. Plan ahead and test before deactivating Mailchimp.
Will I lose my email sending history?
Campaign performance data (open rates, click rates, send history) from Mailchimp cannot be transferred to Sender. Export and save your historical reports from Mailchimp via your profile icon → Account → Settings → Manage my data before migrating. New performance data will begin tracking in Sender from your first send.
Should I import unsubscribed contacts?
Yes. Import your suppression list (unsubscribed and bounced contacts) into Sender with the correct status to avoid sending to contacts who have opted out. This protects your sender reputation and ensures compliance with anti-spam regulations.
Do I need to re-verify my sending domain in Sender?
Yes. Even if your domain was verified in Mailchimp, you need to add it in Sender under Account settings → Domains and configure the SPF, DKIM, and DMARC records that Sender provides. Mailchimp's DNS records will not work for Sender.
Can I keep both platforms running during migration?
Yes. Keep Mailchimp active until you have fully tested your Sender setup — subscriber data, templates, automations, forms, and domain authentication. Only deactivate Mailchimp after verifying everything works in Sender.
Should I use the direct Mailchimp import or a CSV file?
The direct Import from Mailchimp option in Sender (under Subscribers → Add subscribers) is faster and pulls your lists automatically using an API key. However, a CSV import gives you more control over which contacts and fields to include, and lets you clean your list before importing. Use the direct import for speed or the CSV method for more granular control.
Can Sender's support team help with migration?
Check Sender's support options for assisted migration services. Some plan tiers may include migration assistance. Contact Sender support with details about your Mailchimp account size and the volume of data to discuss available options.
