Validate HighLevel Contact Addresses Automatically with n8n and Lob API

What This Automation Does

This workflow checks new contacts’ mailing addresses from HighLevel CRM to find mistakes or missing parts.

It uses Lob’s Address Verification API to tell if an address can get mail or not.

If the address works, the contact gets tagged “Mailing Address Deliverable” in HighLevel.

If not, it gets tagged “Mailing Address NOT Deliverable” so staff can fix it.

This saves hours of manual checking and stops mail from being lost or returned.

Tools & Services Used

• HighLevel CRM: Sends new contact data via webhook.
• n8n Automation Platform: Links all steps in the workflow.
• Lob.com API: Verifies US mailing addresses using HTTP POST requests.

Workflow Inputs, Processing, and Output

Inputs

• New contact data with mailing address fields from HighLevel via webhook.

Processing Steps

• Receive webhook POST with contact address details.
• Standardize fields using the Set node for address, city, state, zip.
• Call Lob’s US Address Verification API to check if address can receive mail.
• Decide route based on API deliverability response using Switch node.
• Tag contact in HighLevel according to deliverability outcome.

Output

• Contact tagged as “Mailing Address Deliverable” if address passes verification.
• Contact tagged as “Mailing Address NOT Deliverable” if address fails verification.

Beginner Step-by-Step: How To Use This Workflow In n8n For Production

Importing The Workflow

1. Inside the n8n editor, click the Import from File button.
2. Select the downloaded workflow file from this page.

Configuring Credentials and Settings

1. Add your Lob API key under node credentials, using Basic Auth.
2. Update webhook path if needed for your use.
3. Check the HighLevel nodes and set correct tags like “Mailing Address Deliverable” and “Mailing Address NOT Deliverable.”
4. Confirm the mapping for emails and phones to find contacts properly in HighLevel.

Testing And Activation

1. Send test contact data with both valid and invalid addresses to the webhook URL.
2. Check the workflow runs successfully and tags update correctly in HighLevel.
3. Activate the workflow by toggling the active switch in the top right.

If running n8n on your own server or VPS, see self-host n8n for help.

Common Workflow Issues and Fixes

• Webhook Does Not Trigger
  Check that the webhook URL is correctly entered in HighLevel, using POST method.

• Authentication Failed on Lob API Calls
  Verify that the Lob API key is correct and saved under Basic Auth credentials in the HTTP Request node.

• Switch Node Sends All Addresses to One Path
  Confirm the deliverability field text is exactly “deliverable” and matching letter case.

• Contacts Not Tagged in HighLevel
  Make sure email or phone fields from webhook correctly match existing contacts.

Customization Ideas

• Change tag names in HighLevel nodes to fit company preferences.
• Add an Email node after the “NOT Deliverable” path to send alerts automatically.
• Adjust for international addresses using Lob’s international API or other providers.
• Add a Code node before the API call to join secondary address info or check formats.

Summary

✓ Saves time by automating address checks from HighLevel contacts.
✓ Tags contacts clearly based on if addresses can receive mail.
✓ Reduces returned mail and improves client communication.
✓ Easy to set up by importing and configuring keys in n8n editor.