Mailchimp to MailerLite Migration Checklist: 34 Checks in 7 Steps

Disclosure: This article may contain affiliate links. We may earn a commission at no extra cost to you. Our findings are based on independent testing.

Based on our migration test of November 3, 2026 (Mailchimp Free account to MailerLite trial account, small test list), full record: How to move from Mailchimp to MailerLite: what actually carries over (tested). This checklist reorganizes that test, and the preparation around it, into the order we would follow before moving a real list. A few steps below were not part of the hands-on test; those are marked where they appear. Checked against official documentation (November 4, 2026), not a hands-on test.

Most migration problems are not import problems. They are preparation problems that the import makes permanent: the tag structure you meant to clean up, the audience separation that disappears without warning, the three addresses the importer rejects on the first pass. Our own test import ran on four contacts, and it still surfaced a rejected-address list, an audience that flattened into the general pool, and one contact we had not realized was in the list at all, the account owner.

Work through these seven steps before you run the real import. Steps 1 to 3 happen entirely inside Mailchimp. Step 4 is a rehearsal. A rehearsal can catch problems before the full import, although larger lists may reveal additional issues.

Step 1: Before you connect anything

• ☐ Create your MailerLite account first, and finish the onboarding. The importer lives inside MailerLite (Subscribers → Add subscribers → Import from Mailchimp), so the destination account has to exist before anything can move.
• ☐ Decide how you will connect: Mailchimp sign-in, or an API key. Both routes are offered. We used the API key, and one thing is worth knowing if you are on Mailchimp’s free plan: free accounts can still create API keys (Profile icon → Profile → Extras → API keys). Tested in our migration.
• ☐ Decide which Mailchimp audiences are in scope, and which are not. MailerLite uses a single shared subscriber list, and the wizard lets you select more than one Mailchimp audience. We tested only one audience, so we have not verified how separate audiences are represented after a multi-audience import. Check the resulting groups carefully before you commit to a scope. That decision is hard to undo after the fact, so make it now, on paper, not in the wizard.
• ☐ Put sending-domain authentication on the plan now; you will do it in Step 7. Your domain will need to be authenticated in MailerLite before you send for real. We did not perform this step in our test; it is included here from MailerLite’s documentation, not from hands-on testing.

Step 2: Audit your data inside Mailchimp

• ☐ Export a CSV backup of every audience you plan to move. The importer is good; a backup is cheap insurance, and it is the only version of your list that nobody’s wizard can reorganize.
• ☐ Write down every tag you use. In our test, one Mailchimp tag, “beta-readers,” was recreated as a MailerLite group with the expected member in it. Treat your tag list as a draft of your future group list, and verify each one after the import rather than assuming all of them survive.
• ☐ List every custom field, and where each one is used. The wizard offers automatic field mapping, and the standard name fields mapped exactly in our test: Mailchimp’s First Name and Last Name arrived as MailerLite’s Name, Last name and a combined Full Name. We did not seed custom fields in this test, so do not trust the automatic suggestion for yours; you will check each one individually in Step 4.
• ☐ List every segment, and mark which ones are static and field-based. According to MailerLite’s documentation, simple field-based segments can be recreated if the relevant migration option is selected. More complex segments based on engagement, behavioral, or e-commerce data may need to be rebuilt manually. We did not test segment migration ourselves.
• ☐ Inventory your active automations, signup forms, landing pages, email templates, and third-party integrations. Record where each one is used and what needs to be rebuilt or reconnected before switching. The importer moves subscriber data only. Everything on this list has to be rebuilt or reconnected by hand, and Step 7 works from this inventory.
• ☐ Find the internal and test addresses in your audience, including your own. In our test, the Mailchimp account owner’s address was part of the audience and was imported like any other contact. Decide before the import whether those addresses belong in the new list.

Step 3: Fix in Mailchimp first

• ☐ Search your list for plus-addressed subscribers, addresses with a “+” in them, like name+news@gmail.com. All three plus-address aliases in our test were rejected by the importer as “Suspicious formatted email.” You can fix rejected rows later, in the import results screen, but do not silently rewrite a real subscriber’s address to make it pass. Verify the correct destination first, and preserve their subscription preferences.
• ☐ If you use multiple audiences to separate brands, languages or lists, rebuild that separation as tags now. In our single-audience test, the Mailchimp tag became a MailerLite group, but we did not find a separate group for the audience itself. MailerLite’s documentation describes group creation for both lists and tags, so check the resulting groups rather than assuming either outcome.
• ☐ Decide what happens to unsubscribed and unconfirmed contacts, before the wizard asks you. They are excluded by default, and including them is an opt-in on the status step of the wizard. For most senders the default is right: a migration should never quietly reactivate someone who unsubscribed. If you do choose to import unsubscribed or unconfirmed contacts, MailerLite places them in their respective non-active statuses. Importing them does not automatically make them eligible to receive newsletters.
• ☐ Note which segments will not survive, and sketch their replacements. Anything built on campaign activity, purchase history or location and birthday filters needs a MailerLite-side replacement plan (per MailerLite’s documentation). Writing this down now is faster than discovering the gap after the move.

Step 4: Run a small test import first

This step combines findings from our small hands-on test with preparation advice for a real migration. The full step-by-step record is in our migration guide.

• ☐ Rehearse with a separate small test audience when possible, before you import everything. Our test used one audience containing four contacts, and it still produced every finding in this checklist. We did not test importing a selected subset of a larger production audience through the Mailchimp importer.
• ☐ Check the field mapping result contact by contact. Names mapped exactly in our test; custom fields were not part of the test, so yours need individual verification rather than a glance at the summary.
• ☐ Open the “not added” report and fix rejected addresses there. Each rejected row has an Edit action, and correcting the address adds the subscriber on the spot. In our first pass, 3 of 4 contacts were rejected this way; after fixing them in the results screen, all 4 were in.
• ☐ Check the groups that were created. Confirm each tag became a group with the right members, and check whether a separate group was created for the original audience. Our single-audience test did not produce one, although MailerLite’s documentation describes that behavior.
• ☐ Fix the causes in Mailchimp, then use “Sync again” instead of starting over. In our test, “Sync again” reused the existing connection without asking us to reconnect. MailerLite also provides a “Reconnect” option if the connection needs to be restored. When we added a contact in Mailchimp and synced again, exactly one contact was added: none updated, none duplicated. Re-sync is incremental, which is what makes a staged migration practical.

Step 5: Run the full import

• ☐ Select exactly the audiences you scoped in Step 1. Everything selected becomes one pool. This is the last moment where “which audiences” is a choice rather than a cleanup job.
• ☐ Use the automatic field mapping only because Step 4 validated it. “Map the fields for me” was accurate in our test. If your test import showed a custom field landing in the wrong place, map that one manually here.
• ☐ Choose a group for every list and tag, rather than one group for everyone. That is the setting we tested, and it is what turns your tag structure into your MailerLite group structure.
• ☐ Leave the status settings at their defaults unless you deliberately decided otherwise in Step 3. Unsubscribed and unconfirmed contacts stay behind by default; keep it that way unless you have a specific, considered reason.
• ☐ Keep duplicate handling on “Update missing info only.” With the default, blank fields get filled and existing data stays. The alternative, “overwrite all fields,” can erase data with blank values. The wizard itself warns about this on screen.
• ☐ Read the results screen before you close it, and keep the “not added” list. The totals alone do not tell you who is missing. Work the list the way you did in the rehearsal: fix each address, verify it is the right destination, and only then move on.

Step 6: Verify the import, record by record

This step follows the same record-level comparison we describe in how we test email tool migrations: totals are a starting point, not a verification. Do it before you cut anything over. Once real sending starts from the new account, data problems get much harder to untangle.

• ☐ Reconcile the counts properly. Reconcile the source contacts against the import results, accounting separately for added, updated, skipped, and rejected records. Exclude out-of-scope contacts, and account for subscription statuses and duplicate email addresses. Do not assume the raw audience count will match a simple added-plus-rejected total. If the numbers do not close, work out which category explains the gap before you move on.
• ☐ Spot-check individual records: name fields, group membership, subscription status. Pick a handful you know well (a tagged contact, a contact with a custom field, one of the fixed addresses from Step 5) and compare them field by field against Mailchimp.
• ☐ Confirm that nobody who unsubscribed has reappeared as a subscriber. A migration that reactivates people who unsubscribed is a serious compliance risk, not just a cleanup cost. Verify it explicitly.

Step 7: Cut over and verify sending

• ☐ Authenticate your custom sending domain in MailerLite before sending live campaigns. This step follows MailerLite’s documentation; it was not part of our hands-on test.
• ☐ Reconnect your signup forms and integrations to MailerLite. Forms, landing pages and templates do not come across in the import. The importer moves subscriber data, not your sending setup, so every form that fed Mailchimp now needs to feed MailerLite instead.
• ☐ Rebuild your automations in MailerLite, starting from the inventory you made in Step 2. Automation workflows do not transfer. A welcome email is the usual first rebuild. We timed a full welcome-series rebuild: 25 minutes, step by step.
• ☐ Coordinate when the old workflows stop and the new ones start. During the switch, a subscriber can be active in both platforms at once. Set the switchover point deliberately, then verify that subscribers cannot receive duplicate automation emails.
• ☐ Send a small test campaign and check that it actually lands before your first real send from the new platform.
• ☐ Keep the Mailchimp account, and your CSV backups, until the new setup has been verified. If your Mailchimp plan is paid, factor in the cost of keeping both services active during the transition. Re-syncing may help transfer updated subscriber information, but it is not a complete rollback strategy.

The bottom line

None of these steps is difficult. The findings that shaped this checklist, plus addresses rejected on the first pass and an audience-group result that differed from the documentation, were visible in a four-contact test, before anything real was at stake. The segment limits in Step 2 came from the importer’s guidance and MailerLite’s documentation; we did not test segment migration. That is the whole argument for the order above: prepare in Mailchimp, rehearse small, then import once.

If the move is partly about cost and you have not run your numbers yet, do that before Step 5: our MailerLite vs Mailchimp pricing comparison sets out what each platform charges at 1,000, 5,000 and 10,000 subscribers, checked against both vendors’ pricing pages.

Based on a migration test run on November 3, 2026, on a Mailchimp Free account and a new MailerLite trial account, with a small test audience. Steps marked as documentation-based were not part of that test. Interfaces and plan terms change; the test date above is the last verified date for the tested steps in this checklist.