Smart Gmail auto-labeler with Gemini AI & sender history

n8n Gmail AI Auto-Labeler

> An intelligent n8n workflow that automatically classifies and labels Gmail emails using Google Gemini AI, keeping your inbox organized with zero manual effort.

This workflow uses AI-powered classification to analyze email content, learn from sender patterns, and automatically apply appropriate labels while archiving processed emails.

How It Works

1. Trigger: The workflow runs automatically every minute to check for new unread emails (or manually for bulk processing).
2. Check for Existing Labels: Before processing, it verifies if the email already has an AI-assigned label to avoid duplicate processing.
3. AI Classification: If unlabeled, the AI agent analyzes the email using:
   • Sender History Tool - Fetches up to 10 previous emails from the same sender to identify patterns
   • 80% Majority Rule - If 80%+ of sender's past emails have the same label, strongly prefers that category
   • Label Examples Tool - When uncertain, compares the email with existing examples from suspected categories
4. Smart Decision: The AI returns a structured JSON response:

   {
     "label": "Category Name"
   }
   

   Or "None" if no category fits.
5. Apply & Archive:
   • Label Applied → The workflow adds the appropriate Gmail label to the thread.
   • Auto-Archive → Removes the email from INBOX (archives it) to maintain zero-inbox.
6. Loop: Processes the next email in the batch, ensuring all new emails are classified.

Requirements

• Gmail OAuth2 Credentials - Connected Gmail account with API access.
• Google Gemini API Key - Get it here
  • Free tier: 15 requests/minute
• Gmail Labels - Must be created in Gmail exactly as listed:
  • Meetings
  • Income
  • Inquiries
  • Notify / Verify
  • Expenses
  • Orders / Deliveries
  • Trash Likely

How to Use

1. Import the Workflow:

   • Copy the provided JSON file.
   • In your n8n instance → click Import Workflow → select the JSON file.

2. Create Gmail Labels:

   • Open Gmail → Settings → Labels → Create new labels.
   • Use the exact names listed above (case-sensitive).

3. Get Your Label IDs:

   • In the workflow, click "When clicking 'Execute workflow'" manual trigger.
   • Execute the "Get Labels Info" node only.
   • Copy each label's ID (format: Label_1234567890123456789).

4. Update Code Nodes with Your Label IDs:

   Node 1: "Check Label Existence"

   const labelMap = {
     "Label_YOUR_ID_HERE": "Meetings",
     "Label_YOUR_ID_HERE": "Inquiries",
     "Label_YOUR_ID_HERE": "Notify / Verify",
     "Label_YOUR_ID_HERE": "Expenses",
     "Label_YOUR_ID_HERE": "Orders / Deliveries",
     "Label_YOUR_ID_HERE": "Trash Likely"
   };
   

   Node 2: "Convert Label to Label ID"

   const labelToId = {
     "Meetings": "Label_YOUR_ID_HERE",
     "Inquiries": "Label_YOUR_ID_HERE",
     "Notify / Verify": "Label_YOUR_ID_HERE",
     "Expenses": "Label_YOUR_ID_HERE",
     "Orders / Deliveries": "Label_YOUR_ID_HERE",
     "Trash Likely": "Label_YOUR_ID_HERE"
   };
   

5. Set Up Credentials:

   • Gmail OAuth2 → Authorize your Gmail account in n8n.
   • Google Gemini API → Add your API key in n8n credentials.

6. Test the Workflow:

   • Send yourself test emails with clear content (e.g., invoice, meeting invite).
   • Use the manual trigger to process them.
   • Verify labels are applied correctly.

7. Activate for Auto Mode:

   • Toggle the workflow to Active.
   • New unread emails will be processed automatically every minute.

Notes

• Dual Execution Modes:

  • Auto Mode - Gmail Trigger polls inbox every minute for unread emails (real-time processing).
  • Manual Mode - Use the manual trigger to bulk process existing emails (adjust limit in "Get many messages" node).

• AI Learning from Patterns:

  • The workflow applies an 80% majority rule - if 80% or more of a sender's historical emails share the same label, the AI strongly prefers that category for new emails from that sender.
  • This creates intelligent sender-based routing over time.

• Skip Already Labeled Emails:

  • The "Check Label Existence" node prevents re-processing emails that already have an AI-assigned label.
  • Ensures efficient execution and avoids duplicate work.

• Structured AI Output:

  • Uses a Structured Output Parser to ensure the AI always returns valid JSON: { "label": "Category" }.
  • If uncertain, returns { "label": "None" } and the email stays in inbox.

• Background Archiving:

  • After labeling, emails are automatically removed from INBOX (archived).
  • Maintains a zero-inbox workflow while preserving emails under their labels.

• Rate Limits:

  • Google Gemini free tier: 15 requests/minute.
  • Adjust polling frequency if hitting limits.

Example Behavior

• Minute 1: New invoice email arrives → AI fetches sender history → 85% were labeled "Expenses" → applies "Expenses" label → archives email.
• Minute 2: Meeting invite arrives → No sender history → AI analyzes content (Zoom link, time) → applies "Meetings" label → archives email.
• Minute 3: Promotional email arrives → AI compares with "Trash Likely" examples → applies label → archives email.
• Minute 4: Already-labeled email detected → skipped silently.

Label Categories

> If no category fits clearly, the email returns "None" and remains in the inbox.

Customization

• Change Polling Frequency: Edit the "Gmail Trigger" node → pollTimes → mode (e.g., every5Minutes).
• Adjust Email Limit: Modify limit: 10 in "Get many messages" node for manual bulk processing.
• Add Custom Labels: Create in Gmail → Get ID → Update both Code nodes + AI system prompt.
• Modify 80% Rule: Edit the AI agent's system message to adjust the majority threshold.
• Increase Tool Limits: Change limit: 10 in Gmail tool nodes to fetch more historical data.

Author: Muhammad Anas Farooq