Leaving Mailchimp: a two-hour Kit migration

Mailchimp's pricing has crept up four times in the last two years and the UI has crept further in the same direction. Kit (formerly ConvertKit) is the cleanest landing spot for creators and solo operators whose lists sit between 1,000 and 25,000 subscribers and who care about cleanliness of segmentation, not the maximalist marketing stack Mailchimp keeps adding. The migration is roughly two hours of actual work, plus the warm-up week you should plan for deliverability. Below is the order of operations that avoids the mistakes most people make.

What you actually move

The list. The active automations. Your most important opt-in forms. That's it. Resist the temptation to move everything: most Mailchimp accounts have years of dead audiences, expired campaigns, and half-finished automations that should not survive the trip. Treat the migration as a deliberate cull.

What stays behind: campaign performance data older than the last 90 days, audience segments built on disused custom fields, signup forms that were never on a live page, and any list segment under 50 people. If you have not used it in 90 days, leave it.

Step 1: export the list

In Mailchimp, go to Audience → All contacts → Export Audience. You get a CSV with every subscriber's email, status, name fields, and any custom fields you added. Save the file somewhere you'll find it again; you'll need it again at step 3.

Critical: filter the export to subscribed status only before importing into Kit. Mailchimp ships unsubscribes, cleaned addresses, and bounced contacts in the same file by default. Importing those into Kit either re-emails people who explicitly unsubscribed (legally risky) or tanks your sender reputation by emailing dead addresses on day one.

If you have time, run the cleaned list through a verification service (NeverBounce, ZeroBounce, $20 for ~10k addresses) before importing. The difference in opens on the first send is dramatic.

Step 2: map the tag and field schema

Kit organises subscribers around tags and sequences rather than Mailchimp's audience-and-group model. The mapping is roughly:

• Mailchimp groups → Kit tags (each group becomes a tag with the same name)
• Mailchimp interest categories → Kit forms or Kit segments depending on whether the interest was opt-in or inferred
• Mailchimp custom fields → Kit custom fields (Kit only supports text and date types, no dropdowns)

Write the mapping down in a Notion doc before you touch Kit. Two minutes here saves an hour of "wait, which thing is which" later.

Step 3: import into Kit

In Kit, Subscribers → Import → CSV. Upload the cleaned file, map the columns, and tag every subscriber with migrated-from-mailchimp-2026-05 (or whatever date you're doing this). The bulk tag matters for two reasons: you can roll back the whole import if something goes wrong, and you can run the warm-up sequence (step 5) on exactly the migrated cohort.

If your list is over 10,000, Kit will queue the import and email you when it's done. Plan for 20 minutes per 10k subscribers.

Step 4: rebuild your most-used automations

Don't try to recreate every automation. Pick the three most important — usually a welcome sequence, a re-engagement flow, and a product-launch sequence — and rebuild them in Kit using the rough emails as a starting point. Treat the migration as a chance to shorten and sharpen each one.

Kit's automation UI is more limited than Mailchimp's but the constraint is helpful. If you cannot build the flow in Kit, the flow was probably too complex in Mailchimp.

Step 5: the warm-up week

Do not blast your full migrated list on day one. Your sender domain has a reputation built on Mailchimp's IPs; switching to Kit means starting fresh on Kit's IPs. Send to the migrated cohort in waves over five to seven days, starting with the most engaged 10% and expanding outward. Watch the open rate on each wave; a sudden drop means you need to slow the ramp.

In practice this means: day 1, send a "we've moved" email to the top 10% opens-from-last-90-days. Day 3, expand to the top 30%. Day 5, the top 60%. Day 7, the rest. If you have a launch planned, push it back by two weeks so the warm-up isn't competing with the campaign.

Step 6: update the forms on your site

Wherever your Mailchimp form lives — landing page, blog footer, in-article embeds — swap the embed code for the Kit equivalent. Kit's embed snippet is one line; the heavier "Pop-up" and "Slide-in" forms are configured inside Kit itself and need the same JS-only paste-once-per-site script.

Leave the Mailchimp account active for 30 days after you cut over. New subscribers who hit a stale form somewhere you forgot still land in Mailchimp; you can spot them and re-import.

Step 7: cancel Mailchimp

Once 30 days have passed without any new subscribers landing there, cancel. Mailchimp keeps your historical data for at least 60 more days; you can re-export campaign performance if you need it for a year-in-review post. The recurring charge stops the day you cancel.

What you will miss from Mailchimp

The visual email builder is more polished in Mailchimp. Kit's editor is plainer and writer-first. If you send rich newsletters with imagery and complex layouts, you will be making a real trade. Most creators report the simpler builder makes them write better emails; if your brand depends on visual richness, Kit may be the wrong move and Beehiiv or MailerLite might fit better.

The other thing that's harder in Kit: granular segmentation by engagement recency. Mailchimp's "subscribers who opened in the last 30 days" is one click; Kit takes a tag-and-rule combination. Not a dealbreaker for most solos, but worth knowing.

When to do this

The cheapest time to migrate is between launches, not during one. The cheapest time to migrate financially is right before a Mailchimp annual renewal — the savings start the month after, and the migration itself is a fixed cost. If you're past the renewal window and your subscription is monthly, do it the week your monthly send is over.