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How to Move from Mailchimp or Sendy to BillionMail Without Losing Subscribers

Moving your newsletter from Mailchimp (or Sendy, MailerLite, ConvertKit and others) to BillionMail can save a lot of money as the list grows. But a careless move can also wreck your deliverability: import the wrong people, blast them all on day one from a new IP, and you land in spam. This guide does it in a safe order.

Step 0: Get BillionMail ready first
Don't cancel your old tool yet. First make sure BillionMail is installed, DNS is green and a test email arrives in the inbox:

• Install BillionMail and set up DNS.
  
• Send one test campaign to yourself; see your first newsletter.
  

Step 1: Export from Mailchimp
In Mailchimp go to Audience > All contacts and use Export Audience. You get a ZIP file with separate CSV files for subscribed, unsubscribed, non-subscribed and cleaned contacts.

• Import only the subscribed file.
  
• Never import unsubscribed or cleaned contacts as subscribers. Unsubscribed people said no; "cleaned" are addresses that bounced. Importing them is how new servers end up blacklisted (and it's illegal in many countries).
  

From Sendy: open each list, export the active subscribers to CSV, and leave out unsubscribed, bounced and complained ones.

Step 2: Clean and reshape the CSV
BillionMail wants a column called

Code:Copy

email

and, optionally, an

Code:Copy

attributes

column with JSON. In a spreadsheet:

1. Rename the email column to
   Code:Copy

   email
   .
   
2. Delete columns you don't need (Mailchimp exports many).
   
3. If you want first names, build an attributes column, for example
   Code:Copy

   {"FirstName": "Jane"}
   .
   
4. Remove duplicates and save as CSV (UTF-8).
   

Mailchimp tags or groups don't come over automatically. Export a separate file per tag, or keep the tag as an attribute, and recreate them as tags in BillionMail.

Step 3: Create groups and import
Create a group for the imported list under Contacts > Group before you import:


Then import the file under Contacts > Subscribers > Import with Subscription Status Subscribe. The full import walkthrough is in BillionMail contacts, groups and tags. Files over 5 MB need to be split.

Step 4: Rebuild your template
Mailchimp's merge tags don't work in BillionMail. Replace them:

• Code:Copy

  *|FNAME|*
  becomes
  Code:Copy

  {{.Subscriber.FirstName}}
  (if you imported FirstName).
  
• Code:Copy

  *|EMAIL|*
  becomes
  Code:Copy

  {{.Subscriber.Email}}
  .
  
• Code:Copy

  *|UNSUB|*
  becomes
  Code:Copy

  {{.UnsubscribeURL}}
  .
  

You can export a campaign's HTML from Mailchimp and paste it into an HTML template, but check it carefully; tracking code and Mailchimp branding often need removing. More in BillionMail templates.

Step 5: Update your signup form
New subscribers should land in BillionMail, not Mailchimp. Point your website's signup form at BillionMail, or, for a while, export new Mailchimp signups every week and import them. Don't forget forms on landing pages and in pop-up plugins.

Step 6: Don't send to everyone on day one
Your old tool had a warm IP; your server doesn't. Send to your most engaged subscribers first and grow over a few weeks, as described in the IP warm-up plan. Keep the old account open (a free or cheap plan is enough) for a month in case you need to go back.

Tell your subscribers (optional)
Your From address and design probably stay the same, so most people won't notice. If your From domain changes, mention it in the first email and ask people to add the new address to their contacts. That small step helps a lot with inbox placement.

More BillionMail guides

• Send API for transactional email
  
• WordPress email through BillionMail SMTP
  
• Import contacts, groups and tags
  
• Email templates explained
  
• SMTP relay with Amazon SES, Brevo or Mailgun
  
• Mailboxes and webmail
  
• Campaign analytics explained
  
• IP warm-up plan
  
• Add a second sending domain
  
• Send your first newsletter · DNS setup explained · Deliverability testing
  

Applies to BillionMail 4.9, October 2026. Replace

Code:Copy

example.com

and

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mail.example.com

with your own domain and mail hostname. Menu names can change a little between versions.