Build mailing lists

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Build mailing lists

Last updated April 21, 2026 14:22

Collect and organize subscriber email addresses into mailing lists for email campaigns.

A mailing list is a collection of email addresses. When you're ready to send an email campaign, you'll send it to one or more mailing lists.

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Create a mailing list

Create a mailing list in the Contacts panel under Lists & Segments.

  1. Open the Lists & Segments panel.
  2. Click Create Mailing List and give the mailing list a name. You can have up to 20 mailing lists.
  3. Click Add Subscribers to either add subscribers individually or upload a .csv of existing subscribers. Mailing lists have no subscriber limit, but if a list has more than your monthly send limit, you can't send campaigns to that list.

Note: Ensure you have permission to send emails to every subscriber on your list. If you're sending commercial messages, review the legal requirements for your country and the country of anyone you're emailing, such as CAN-SPAM, CASL, and PECR.

Add subscribers to your mailing list individually

To add a subscriber:

  1. Open the Lists & Segments panel and click the mailing list.
  2. Click Add Subscribers, then click Add an individual subscriber.
  3. Add the email address and the subscriber's first and last name (optional). If you're pasting an email address, ensure you paste it as plain text.
  4. Switch on the These subscribers accept marketing toggle to confirm you have permission to send this subscriber marketing emails.
  5. Click Done.

Import subscribers to your mailing list in bulk

You can import a .csv list of contacts that you've exported from another email marketing service:

  1. Open the Lists & Segments panel and click the mailing list.
  2. Click Add Subscribers, then click Upload a list.
  3. Click Add a CSV file to select a file to import from your device.
  4. Switch on the These subscribers accept marketing toggle to confirm you have permission to send these subscribers marketing emails.
  5. Preview your list, then click Import.

Prepare the subscriber .csv file before you import it

The subscriber import .csv file needs to be formatted correctly before you can import it. Ensure the file:

  • Has 500,000 contacts or fewer.
  • Has a file name with only basic alphanumeric characters. A file name with special or accented characters may cause the upload to fail.
  • Has no more than three columns, arranged in this exact order. Any columns after the first three in your .csv file are ignored.
  • Email address
  • First name (optional)
  • Last name (optional)

Review an example .csv file

If your .csv file has different data in the first three columns, our system still imports them regardless of how they're titled or what kind of information is in them. For example, if your third column has middle names, they'll be imported into your list as last names.

CSV file looks like a spreadsheet with three columns for email address, first name, and last name. Example email addresses and names fill the rows.

How the import handles duplicate contacts

If you upload mailing lists with duplicate contacts, our system excludes the duplicates.

What happens if you import an unsubscribed contact

If someone unsubscribes from a mailing list in Squarespace, uploading a .csv with their email address to the same mailing list won't resubscribe them.

Troubleshoot common error messages

Error message: You must enter a valid email address

This error displays when the email address entered is not valid. If the email address looks correct, ensure there aren't extra spaces before or after the text, especially if you copied and pasted the address from elsewhere. When copying and pasting email addresses into your mailing list or .csv file, ensure you paste them as plain text to avoid unsupported characters or formatting.

Error message: Improperly Formatted

If an Improperly Formatted error message appears, ensure your .csv file is formatted correctly. In particular, ensure the first column contains email addresses. If it doesn't, the error message appears.

Depending on their settings, some spreadsheet programs may not export .csv files correctly. For example, they may use semicolons to separate values instead of commas. If that's the case, contact your spreadsheet program's provider for help changing this setting, or try exporting your mailing list from a different program and importing again.

Error message: Upload Failed

If an Upload Failed error message appears, your mailing list has addresses that may cause high bounce rates and spam reports. Review our best practices and revise your list.

Collect mailing list subscribers through sign up forms

Create newsletter signup forms to collect new subscribers for your mailing lists. You can connect a mailing list to these areas:

Delete a mailing list

To delete a mailing list:

  1. Open the Lists & Segments panel.
  2. Click •••on the list you want to delete.
  3. Click Delete, then click Delete again to confirm. You'll be alerted if the mailing list is still connected to a form somewhere on your site.
  4. If the list was connected to a sign up form, replace it with a different, active list in the form storage settings. If visitors sign up through a form connected to a deleted mailing list, they won't be added to a mailing list, but they will appear in the Subscriberssmart segment.

Remove a subscriber

Subscribers can remove themselves by clicking the Unsubscribe link in your campaign. To remove subscribers from a mailing list:

  1. Open the Lists & Segments panel.
  2. Click a mailing list.
  3. Select contacts.
  4. Click Remove from list, then click Remove.
  5. Keep in mind, this only removes the subscriber from this mailing list. It won't affect other mailing lists or delete them from your Contacts panel. To remove the contact from your site entirely, delete it in the Contacts panel.

Copy or move contacts between mailing lists

To copy or move contacts to a different mailing list:

  1. Open the Lists & Segments panel.
  2. Click a mailing list.
  3. Select contacts.
  4. Click Copy to or Move to, select the list, then confirm.

Rename a mailing list

To change a mailing list name:

  1. Open the Lists & Segments panel.
  2. Click ...on the list you want to rename.
  3. Add the new name, then click Save.

Search subscribers

To search a mailing list for a subscriber:

  1. Open the Lists & Segments panel and click the mailing list you want to search.
  2. Click into the search field and begin typing their first name, last name, or email address.
  3. Results filter in real-time as you type your search criteria.

Edit subscribers

If a contact only has an email address and no name, or it has an outdated, incorrect, or incomplete name, you can edit the first and last name. To edit the contact's name through a mailing list:

  1. Open the Lists & Segments panel, then click the mailing list with the contact you want to edit.
  2. Click the contact.
  3. Click Full Profile.
  4. Click the pencil icon next to their name.
  5. Edit the first and last name, then click Save. Keep in mind, this updates the contact's name on all lists and segments in your site.

Export mailing lists from Squarespace

To download a .zip file that includes three .csv files (subscribed users, unsubscribed users, and cleaned users):

  1. Open the Lists & Segments panel.
  2. Click ... on the list you want to export.
  3. Click Export.

Export mailing lists from other providers

Most providers let you export your contacts as a .csv list. You can then import those contacts into an Email Campaigns mailing list.

For example, to export your list of contacts from Mailchimp:

  1. Log into Mailchimp.
  2. Click Audiences and click the audience you want to download.
  3. Click Export Audience.
  4. An Exporting message appears.
  5. The Exporting message turns into an Exported message. (You may need to refresh the page.)
  6. Click Export as CSV. The audience will download as a .zip file to your computer.
  7. Open the file so it unzips. You'll see a Subscribed list and an Unsubscribed list.
  8. Import the subscribed list into Squarespace Email Campaigns.

To export mailing lists from other providers, visit their documentation:

Troubleshoot missing contacts

There are a few reasons why emails may not show up on a mailing list, depending on the situation.

The contact didn't confirm their subscription

If you have confirmation emails enabled for subscriber verification, subscribers who sign up with a newsletter block, promotional pop-up, or cover page newsletter sign-up must click the link in that email before they're added to the mailing list.

The contact didn't receive the confirmation email

If the person says they haven't received that confirmation email, ask them to check their spam folder. You can disable the confirmation email in some cases. To learn more, visit Subscriber verification.

The contact unsubscribed

When someone clicks Unsubscribe in your campaign footer, their name and email address are removed from all mailing lists. To learn more, visit Email campaign unsubscribes.

The contact was cleaned

Squarespace automatically “cleans” (removes) email addresses that “hard bounce,” which means they aren't connected to a valid inbox. Removing these email addresses reduces bounce rates and helps improve deliverability for all your campaigns.

Send email campaigns to mailing lists

When you're ready to send your campaign, you'll select one or more mailing lists in the Email tab of your campaign draft. To learn more, visit Sending email campaigns.

Learn how to build successful mailing lists

For tips on building a successful, healthy mailing list, visit our best practices before adding contacts.

Register for a webinar

Register for our Engage Your Audience with Email Campaigns webinar where we’ll walk you through how to use Email Campaigns, Squarespace’s built-in email marketing tool, to grow and engage your audience. You’ll learn how to build mailing lists, create and send campaigns, and measure campaign performance with our analytics tools.

Hire an expert

If you get started and decide you want more hands-on help, you can hire a vetted Squarespace Expert.

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Build mailing lists