Automate Subscriber Management with MailerLite in n8n

Opening Problem Statement

Meet Harshil, a newsletter manager who spends hours every week manually managing subscriber information in MailerLite. He often enters subscriber emails, updates city details, and double-checks subscriptions one by one. This process is cumbersome and error-prone, leading to duplicated records, inconsistent custom field updates, and wasted time that could be better spent on crafting engaging content for his audience.

Specifically, Harshil wastes nearly two hours weekly performing repetitive tasks of creating, updating, and verifying subscriber information manually. Mistakes in updating custom fields like city lead to mis-targeted campaigns and lost marketing opportunities.

What This Automation Does

This n8n workflow automates the entire subscriber management cycle in MailerLite with the following outcomes:

• Creates a new subscriber with predefined email and name fields automatically via API.
• Updates existing subscriber details, specifically custom fields such as city.
• Fetches updated subscriber information instantly for verification or downstream processes.
• Eliminates manual data entry steps, reducing human errors and improving data accuracy.
• Streamlines synchronized subscriber data management within MailerLite through a seamless n8n chain.
• Saves up to two hours of manual work each week when managing subscriber data.

Prerequisites ⚙️

• n8n Account: A functioning n8n instance, either cloud-hosted or self-hosted.
• MailerLite Account 🔑: An active MailerLite account with API credentials.
• MailerLite API Credential Configuration 🔐: Proper MailerLite API credentials added to n8n for authentication.
• Basic Working Knowledge of n8n Interfaces: Comfort navigating nodes and workflows.

Optional: If you prefer to self-host n8n for better control and security, you can explore hosting options with providers like Hostinger.

Step-by-Step Guide

Step 1: Trigger the Workflow Manually

Navigate to the n8n editor and start with the Manual Trigger node. Click Execute Workflow to initiate the process manually. This node simulates a manual start to test and run the subscriber management automation.

You will see the manual trigger node light up indicating the workflow is activated.

Common Mistake: Forgetting to click “Execute Workflow” will leave the automation inactive.

Step 2: Create Subscriber in MailerLite

Following the manual trigger, the workflow passes data to the first MailerLite Node. Configure it with:

• Operation: (default is create subscriber)
• Email: Enter [email protected] as in the workflow.
• Name (custom field): Set to Harshil in the additionalFields object.

This config will create a new subscriber or find the subscriber by email in MailerLite if it exists.

Outcome: A subscriber record is created with the specified email and name.

Common Mistake: Using wrong API credentials causes authentication errors.

Step 3: Update Subscriber’s Custom Field

The created subscriber’s email is passed dynamically to the next MailerLite Node (Update operation). The node is configured to update a custom field “city” with value “Berlin”):

• operation: update
• subscriberId: Referenced dynamically from the previous node’s email field using = {{$node["MailerLite"].json["email"]}}
• customFieldsUi: Setting custom field city to Berlin

Outcome: The city custom field is updated for the subscriber.

Common Mistake: Not mapping subscriberId correctly will cause update failures.

Step 4: Retrieve Updated Subscriber Info

The workflow then calls the last MailerLite Node (Get operation) to fetch the updated subscriber details. This uses:

• operation: get
• subscriberId: Again, dynamically set from the first MailerLite node’s email.

Outcome: The final subscriber data, including updated custom fields, is fetched and ready to be used or logged.

Common Mistake: Using static subscriber IDs instead of dynamic expressions can break automation on new subscribers.

Customizations ✏️

• Change Subscriber Email and Name: In the first MailerLite node, modify the email and additionalFields.name fields to your own subscriber details.
• Add More Custom Fields: In the update MailerLite node, add more entries under customFieldsValues to update multiple subscriber fields like phone or country.
• Automate via Different Trigger: Replace the Manual Trigger node with a webhook or schedule trigger to automate on real-time events or timed intervals.

Troubleshooting 🔧

Problem: “Authentication Failed in MailerLite Node”

Cause: API key was not added correctly or expired.

Solution: Go to n8n Credentials → MailerLite API → Re-enter your valid API key and save. Re-run workflow.

Problem: “Subscriber update failed due to invalid subscriberId”

Cause: Incorrect subscriber ID mapping from previous node.

Solution: Ensure the update and get nodes reference the subscriberId dynamically from the first MailerLite node’s email field using the correct expression syntax.

Pre-Production Checklist ✅

• Verify MailerLite API credentials are current and tested.
• Test manual trigger to ensure workflow starts as expected.
• Run full workflow and confirm subscriber is created, updated, and retrieved successfully.
• Check output data from each node to validate API response formats and field values.
• Backup any important subscriber data before running for live use.

Deployment Guide

To deploy, simply activate the workflow in n8n by toggling the active switch and save. Since this workflow uses a manual trigger, for production use, consider replacing it with a Webhook Trigger or Schedule Trigger to automate subscriber management in production environments.

Monitor the executions tab in n8n to track success and errors for ongoing maintenance.

FAQs

• Can I update other custom fields besides city? Yes, you can add multiple custom fields in the update node configuration.
• Does this workflow consume MailerLite API credits? MailerLite API calls are generally free up to your plan limits; check your MailerLite pricing plan.
• Is my subscriber data secure? Yes, data is transmitted securely via MailerLite API and n8n credentials management.
• Can I replace Manual Trigger with another trigger? Absolutely, using Webhook or Schedule triggers is recommended for continuous automation.

Conclusion

By following this tutorial, you successfully automated subscriber management in MailerLite—creating, updating, and fetching subscriber details seamlessly through n8n. This frees up hours of manual work for Harshil and improves data quality for targeted campaigns.

Next, you might explore automations to send welcome emails upon subscriber creation or segment subscribers based on the city custom field updated here. This workflow is a solid foundation to build scalable email marketing automations with n8n and MailerLite.