For lists under about 5,000 contacts the free tier can still be a marketing list while you operate the publication, which makes the transition less abrupt.

What actually transfers from Mailchimp?

Substack’s model is simpler than Mailchimp’s by design. It’s a publication platform, not a marketing automation suite. If you run a 6-email onboarding sequence today, it doesn’t exist after the move. That alone changes the plan.

Step 1: Export and clean before you import

In Mailchimp, go to Audience > All contacts > Export Audience, choose the whole audience, and download the CSV. Clean it locally:

• Remove contacts with unsubscribed or cleaned status.
• Remove the Non Subscribed and Transactional groups if you have them.
• Deduplicate by email, keeping the row with the most recent activity date.

Importing your unsubscribes back into a new platform is the fastest way to earn spam complaints. Substack doesn’t know they opted out of anything.

Step 2: Import in batches, not in one shot

Substack’s import accepts CSV under Settings > Import. Large single files fail more often than batches of 500, and a failed import part-way leaves you unsure what landed. Do 500 at a time and check the subscriber count after each batch.

Map columns explicitly. Substack guesses email and name, and it will quietly drop a column it doesn’t recognise rather than erroring — which looks like a clean import with missing data.

Step 3: Decide about re-consent

This is the part with legal weight. If your Mailchimp list was built with a checkbox that said “Mailchimp newsletters”, you do not have automatic permission to send from Substack under a different brand. In practice most small lists transfer fine under the same business name, but if the publication is a new name on a new domain, send one plain-text note before importing: here’s where I’m moving, click to keep receiving.

Substack can’t send that note to people who aren’t subscribers yet, so use Mailchimp for the announcement. Keep the list in Mailchimp for 30 days to run it.

Step 4: Warm up deliverability

The first Substack send to a transplanted list lands from a new sending domain. Two things matter: send your first post to a small segment first (say your 50 most engaged), then the rest; and make sure the From address and publication name match what people recognise.

Expect 5-10% of an old list to never receive again — stale addresses, corporate filters, people who used the newsletter as a formality. That’s normal and not a sign the migration failed.

Step 5: Rebuild the one automation that matters

You can’t rebuild a six-email onboarding flow. You can rebuild the important half: the welcome email on subscribe plus one follow-up. Put your best archived post in the follow-up. Substack lets you schedule this, and it’s the highest-value item in the whole migration.

Is it worth moving at all?

Yes if your main pain is Mailchimp’s cost scaling with list size while your revenue is from paid subscriptions. Running the numbers: a 10,000-contact Mailchimp list at roughly $100/month against Substack’s 10% of paid revenue — Substack becomes cheaper once you’re doing more than about $1,000/month in paid subs.

No if you depend on segmentation, shopping integrations or behavioural triggers to sell. Substack has no equivalent, and you’ll lose measurable revenue, not just convenience. Teams in that position are better served by an email provider with subscriber pricing and a separate paid-content layer.

Quick Summary

• Mailchimp to Substack import moves email and name only.
• Tags, segments, automations, open history and purchases do not transfer.
• Export, remove unsubscribes and deduplicate before importing.
• Import in 500-row batches and verify the count after each batch.
• Keep Mailchimp live for 30 days to send the migration announcement.

What does Substack cost a new writer?

Nothing to start. No monthly hosting fee, no email send fee, no theme purchase. Substack’s cut is 10% of gross paid revenue, and Stripe takes roughly 3%. On a $8/month subscription, that’s about $6.90 in your pocket per paid reader per month.

Compare that with a self-hosted stack: email platform at $30-100/month, domain, and payment processing. Substack wins until you have real revenue, then the 10% starts to feel expensive. Break-even math: at $3,000/month revenue, the 10% is $300 — comparable to running Ghost plus ConvertKit yourself, with far more work.

Step 1: Pick a topic narrow enough to be referred to

“Writing about tech” is not a beat. “What AI coding tools actually cost enterprise teams” is. The test: can a reader describe your newsletter to a colleague in one sentence? If not, pick again.

You also need a posting rhythm you can sustain. Weekly is the standard, and weekly is harder than it sounds after week nine. Biweekly is honest for most people starting alongside a day job.

Step 2: Turn on payments, but keep a large free tier

In Settings > Payments, connect Stripe. Then resist the urge to make everything paid. The conventional and still correct structure:

• 100% of posts free for the first 6-8 weeks
• After that, paid posts every 2-3 weeks, free posts in between
• Never paywall the archive of your earliest posts

Paid conversion on Substack typically lands between 2% and 8% of free subscribers. A 5% rate is a good outcome for a niche publication with a clear value promise. Getting to 100 free subscribers before turning on the paywall is the threshold where conversion numbers stop being noise.

Step 3: Price at a number you’d defend out loud

Common price points on Substack: $5, $8, $10, $12 monthly, with annual at roughly 2 months free (around $80/year for an $8 monthly). Pick monthly in the middle of the range and annual at a 17-20% discount.

Cheap isn’t automatically better. A $5 newsletter can attract readers who churn on the first skipped week. $8-10 filters for intent and gives you room to add a paid tier later without a painful migration.

Step 4: Write the welcome email and the About page first

Both do more work than any single post. The About page converts visitors; the welcome email converts subscribers into readers. Substack sends a default welcome — replace it. Three sentences: who you are, what arrives and when, and one link to your best post.

You can edit it under Settings > Emails, and new subscribers get the new version only. Test by signing up with a second email.

Step 5: Get the first 100 subscribers without ads

Substack’s own recommendation network is the highest-yield lever available. Turn it on under Settings > Recommendations, add 5-10 publications in adjacent niches, and ask two to reciprocate. This alone can drive 20-40 subscribers a month once it settles.

The rest comes from places you already have standing: replying to a thread in a community you actually belong to, one post a month cross-posted to a relevant subreddit with real substance, and an email signature. Paid ads before 500 subscribers tend to buy the wrong readers.

What about Notes and the Substack app?

Notes work for writers who enjoy it. It’s a feed, and feeds reward volume. If you’ll post two Notes a day, it’s a real growth channel; if you’ll do it twice a month, skip it and put the energy into posts.

When is Substack the wrong choice?

If you need full design control, a paywall on a corporate site, or to keep your email list portable, Substack is a compromise. Your subscriber list exports as CSV, but the relationship lives on their platform and recommendation graph. Publishing companies and people with an existing WordPress audience often do better building on a platform they control, especially once revenue passes a few thousand a month.

Quick Summary

• Substack is free to start; it takes 10% of paid revenue on top of Stripe fees.
• Publish free for the first 6-8 weeks, then introduce paid posts every 2-3 weeks.
• Typical paid conversion runs 2-8% of free subscribers.
• $8/month with an annual option around $80 is a safe starting price.
• Recommendations and Notes are the two growth levers that cost nothing.