ESPs and CRMs

MailerLite

Overview

Connecting RightMessage with MailerLite lets you sync quiz and survey responses, segment your audience based on visitor behavior, and personalize content using MailerLite subscriber data. This integration supports two-way data sync for custom fields, groups, and tags.

Before you begin

You'll need:

  • An active MailerLite account with API access

  • Your MailerLite API key (from your account settings)

  • A published RightMessage site with the tracking script installed

RightMessage supports one ESP integration per site. If you're switching from another ESP, disconnect it before connecting MailerLite.

Step 1: Get your MailerLite API key

  1. Log in to your MailerLite account

  2. Navigate to Integrations in the left sidebar

  3. Click Developer API

  4. Copy your API key (it starts with a long string of characters)

Keep your API key secure. It grants full access to your MailerLite account data. Never share it publicly or commit it to version control.

Step 2: Connect MailerLite to RightMessage

  1. In RightMessage, go to Settings → Integrations

  2. Find MailerLite in the list of available integrations

  3. Click Connect

  4. Paste your API key into the field

  5. Click Connect to test the connection

RightMessage will verify your credentials by connecting to the MailerLite API. If successful, you'll see your MailerLite groups, fields, and tags become available for mapping.

Step 3: Identify returning subscribers

To personalize content for known MailerLite subscribers, RightMessage needs to identify visitors when they arrive at your site. There are two ways to do this:

Add a parameter to links in your MailerLite emails so RightMessage can identify subscribers when they click through.

  1. In your MailerLite email campaigns, append ?ml_id={{$email}} to links pointing to your website

  2. Example: https://yoursite.com/blog?ml_id={{$email}}

  3. When subscribers click these links, RightMessage automatically identifies them and loads their data

Method 2: Capture from form submissions or thank-you pages

If subscribers fill out a MailerLite form on your site, you can identify them on the thank-you page:

  1. In your MailerLite form settings, enable "Redirect to thank you page"

  2. Set the URL to include the subscriber ID: https://yoursite.com/thank-you?ml_id={{$email}}

  3. Make sure your RightMessage tracking script is installed on the thank-you page

For best results, use both methods. This ensures RightMessage can identify subscribers whether they arrive from emails or sign up through your site.

Step 4: Map fields, groups, and tags

Once connected, you can sync data from RightMessage Flows to MailerLite. This happens when you configure individual quiz questions, survey responses, or adaptive form fields.

Syncing custom fields

  1. Create or edit a Flow in RightMessage

  2. Add a question or response field

  3. In the question settings, scroll to Sync to MailerLite

  4. Select Sync to custom field

  5. Choose an existing MailerLite custom field or create a new one

  6. Save and publish your Flow

When someone completes your Flow, their response will sync to MailerLite as a custom field value on their subscriber record.

Applying tags

Tags work similarly to groups:

  1. In your Flow question settings, find Sync to MailerLite

  2. Select Apply tag

  3. Choose or create tags to apply based on the response

  4. Publish your Flow

Step 5: Use MailerLite data for personalization

Once data is syncing, you can personalize content on your website and in CTAs (like Offers) using MailerLite subscriber information.

Display dynamic content with merge tags

Use these merge tags in your content widgets, popups, and personalized blocks:

  • {{ mailerlite.email }} – subscriber's email address

  • {{ mailerlite.firstName }} – first name (if available)

  • {{ mailerlite.lastName }} – last name (if available)

  • {{ mailerlite.customFields.field_name }} – any custom field value

Use the safe navigation operator ? for optional fields: {{ mailerlite.firstName? }}. This prevents errors if the field is empty.

Troubleshooting

Connection fails or returns an error

  • Verify your API key is correct (no extra spaces)

  • Check that your MailerLite account has API access enabled

  • Confirm your API key has not been regenerated (old keys stop working)

Data not syncing to MailerLite

  • Make sure your Flow is published (drafts don't trigger syncs)

  • Check that the subscriber completed the entire Flow

  • If using double opt-in in MailerLite, custom fields and tags won't update until the subscriber confirms their email

  • Review your Flow's integration settings to confirm fields are mapped correctly

Subscriber not identified on website

  • Confirm the tracking parameter (ml_id) is appended to your email links

  • Verify the RightMessage tracking script is installed on the destination page

  • Check browser console for JavaScript errors that might block the script

  • Test with incognito/private browsing to rule out cached data

Custom fields not appearing

  • Wait a few moments after connecting—RightMessage fetches fields from MailerLite's API

  • Refresh the RightMessage settings page

  • Verify the custom field exists in MailerLite (or let RightMessage create it automatically)

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