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How to move subscribers from beehiiv, Substack or Mailchimp with Mailcheap

Import a CSV export from another newsletter tool with each reader's status and signup date kept.

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Authorization notice. Mailcheap is dual-use. Only use it on software, sites and systems you own or have explicit permission to test.

Credentials. Subscriber CSVs contain personal email addresses, so delete local copies once the import is confirmed.

Who it is forA newsletter owner leaving beehiiv, Substack, Mailchimp or another listed tool to cut costs.

The problemMoving a list is risky: invalid, misspelled or previously unsubscribed addresses can hurt deliverability, and re-importing them can resend to people who opted out.

The outcomeA cleaned contact list in MailCheap, with readers' statuses and signup dates intact and bad addresses left out automatically.

What you need first

  • A MailCheap Cloud account at mailcheap.ai, or a server with Node.js 22+ and a MongoDB database for self-hosting
  • For self-hosting: an Amazon SES or PostShiba account, plus Upstash QStash for background sending
  • A list of contacts with consent to email them, or an export CSV from beehiiv, Substack, Mailchimp or another supported tool
  • An AI agent or API key if you want an agent to write or send issues

Steps

  1. Export your subscriber list as CSV from beehiiv, Substack, Mailchimp, Kit, MailerLite, Buttondown, Ghost or EmailOctopus.
  2. Import the CSV into your MailCheap newsletter as it is.
  3. Review what the import left out: invalid, misspelled, spam trap, role, throwaway, duplicate and domains that cannot receive email.
  4. Check that the never-email list has not blocked addresses you expected to keep, and that unsubscribed or complained readers stayed out.
  5. Leave list cleanup on, so readers who ignored several issues get one re-engagement email and then stop receiving issues.

Prompt for your agent

Using the marclou/mailcheap MCP server with my API key, import the CSV at <path to export file> into the newsletter <newsletter name>. Report how many contacts were imported and how many were left out by reason. Do not send any issue. Verify that the reader count in the dashboard matches the import report.

Caveat. Imports only bring over contacts the cleaning rules allow, so expect some addresses to be left out and check the report before you assume the list is complete.

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