Automate Microsoft Outlook Email Categorization with AI in n8n

1. Opening Problem Statement

Meet Sarah, an operations manager at a mid-sized company who handles hundreds of emails daily. Each morning, she spends over two hours sorting through her Microsoft Outlook inbox, flagging urgent messages, categorizing them, and prioritizing tasks. Manual sorting often leads to missed urgent emails and inconsistent tagging, causing delays and productivity loss. Sarah needs a better way to manage her inbox without spending hours every day on repetitive work.

This exact problem is what the Microsoft Outlook AI Email Assistant workflow solves by automating email categorization and prioritization using AI integrated within n8n.

2. What This Automation Does

When this n8n workflow runs, it systematically:

• Fetches unread and unflagged emails from a specific Outlook folder using filtering rules to avoid reprocessing already tagged or flagged emails.
• Sanitizes the email content by stripping out HTML and unnecessary characters, preparing it for AI analysis.
• Retrieves contact details from Monday.com and stores them in Airtable for up-to-date CRM context during email processing.
• Applies AI-based categorization and sub-categorization to emails leveraging GPT-4o via Langchain nodes, considering sender information, subject, and body.
• Automatically updates email categories and, if applicable, sets the importance to High based on AI recommendations.
• Allows you to maintain your categorization rules, delete rules, categories, and contacts dynamically through Airtable for customized processing.

By automating these steps, Sarah could save at least 10 hours per week, reduce missed critical emails significantly, and maintain a well-organized inbox effortlessly.

3. Prerequisites ⚙️

• n8n account for workflow orchestration (self-hosting option available for full control)
• Microsoft Outlook account with OAuth access configured in n8n (Microsoft365 Email Account credential)
• OpenAI account with GPT-4o access integrated into n8n (OpenAI API credential)
• Monday.com account with API access to retrieve contact data (Monday.com API User credential)
• Airtable account with Personal Access Token configured in n8n to store Contacts, Categories, Rules, and Delete Rules

4. Step-by-Step Guide to Building the Workflow

Step 1: Trigger the Workflow Manually or via Scheduler

Navigate to the Trigger node, which is set as Manual Trigger for testing or can be replaced with a Schedule Trigger to run every 15 minutes.

Tip: During development, testing manually helps verify each step before automation.

Step 2: Retrieve Unprocessed Emails from Outlook

Click + Add Node → select Microsoft Outlook. Set operation to getAll, limit to 10 emails per run.

Under filters, apply the OData filter: flag/flagStatus eq 'notFlagged' and not categories/any() to exclude flagged or categorized emails.

Select the folder ID of your target inbox folder to scan (specific folder in Outlook).

You should see fetched emails’ key fields like subject, sender, body. This ensures we only work on fresh emails.

Step 3: Convert Email Body from HTML to Markdown

Add the Markdown node to transform the HTML email body to plain markdown text, making it easier for AI to understand.

Step 4: Sanitize Email Content

Create a Set node to clean and strip unnecessary HTML tags and special characters from the email body and select fields such as subject, importance, sender email, etc.

Use this JavaScript snippet inside the Set node for the body field (replace all unnecessary tags and characters):

{{$json.data
  .replace(/<[^>]*>/g, '')
  .replace(/[(.*?)]((.*?))/g, '')
  .replace(/![.*?](.*?)/g, '')
  .replace(/|/g, '')
  .replace(/-{3,}/g, '')
  .replace(/n+/g, ' ')
  .replace(/([^ws.,!?@])/g, '')
  .replace(/s{2,}/g, ' ')
  .trim()
}}

This prepares a clean text ready for AI processing.

Step 5: Retrieve Contact Data from Monday.com

Add a Monday.com node to fetch all contacts from your Monday board’s topics group, for context-aware email classification.

Step 6: Sync Contacts to Airtable

Add an Airtable – Contacts node to upsert contact records ensuring your contact list is always current.

Step 7: Fetch Categorization Rules, Categories and Delete Rules from Airtable

Add three separate Airtable nodes to fetch your dynamic categorization rules, categories, and delete rules. This gives you control over your email AI classification logic.

Step 8: Loop Over Each Email to Process Individually

Use the SplitInBatches (Loop Over Items) node to process emails one by one through the workflow instead of bulk processing.

Step 9: Match Email Sender to Contacts in Airtable

Add an Airtable node with a filter formula to find senders in your contacts list by matching the email address.

Step 10: Use AI Agent Node for Email Categorization

Add the AI: Analyse Email node (Langchain Agent) configured with:

• System message instructing AI to categorize only with predefined categories and optionally mark as “Action” subcategory.
• The input email’s sanitized subject, body, sender info, and contact list.
• Output JSON format strictly defined to include email id, subject, category, subCategory, and analysis.

This node runs GPT-4o via OpenAI to classify the email intelligently.

Step 11: Parse AI Output for Structured Data

Add the Structured Output Parser node configured with the JSON schema to validate and extract fields from the AI response cleanly.

Step 12: Update Email Category in Microsoft Outlook

Add the Microsoft Outlook node with update operation to tag the email with the AI-assigned category.

Use the email id from AI output to specify the message.

Step 13: Prioritize Action Required Emails

Add a condition If node checking if the AI subCategory is “Action”. If true, pass to a node that updates the email’s importance to High in Outlook using an update operation.

5. Customizations ✏️

• Adjust Email Filters: In the Microsoft Outlook node filters, change the OData filter expression to include other flags or categories to refine which emails get processed.
• Expand Categories in Airtable: Add or remove categories with detailed usage and sender indicators in your Airtable ‘Categories’ table to customize AI classification.
• Change AI Model Parameters: Adjust temperature or switch GPT models in the OpenAI Langchain node to influence categorization behavior and creativity.
• Integrate Different CRM: Replace Monday.com with another CRM node or API to provide contact data for AI context.
• Expand Email Actions: Add further Microsoft Outlook nodes to automate replies, move emails to folders, or flag them based on categories.

6. Troubleshooting 🔧

Problem: “No emails fetched from Outlook node.”
Cause: The filter expression or folder ID may be incorrect.
Solution: Verify folder ID corresponds to your mailbox folder. Test filter expression by removing it temporarily to check if emails are fetched. Check Outlook credentials.

Problem: “AI agent returns invalid JSON or fails classification.”
Cause: Input data not cleaned or AI prompt instructions are ambiguous.
Solution: Ensure email body sanitization is thorough, check system message prompt syntax is correct in the AI node. Also, check internet/API connectivity.

Problem: “Contacts from Monday.com not syncing to Airtable.”
Cause: API keys or configurations incorrect.
Solution: Double-check Monday.com API token, Airtable API tokens and board/table IDs. Run each node independently to test data flow.

7. Pre-Production Checklist ✅

• Confirm Microsoft365 credentials have required mailbox permissions.
• Verify Airtable bases and tables exist with proper column mappings.
• Test OpenAI connection with a simple prompt in the AI node.
• Validate Monday.com board and group for contacts retrieval.
• Run the workflow manually and verify emails are fetched, processed, and updated in Outlook.
• Back up your Airtable and Monday.com data before first production run to avoid data loss.

8. Deployment Guide

Activate the workflow by enabling the trigger (manual or schedule). Schedule triggers can run every 15 minutes for near real-time email management.

Monitor workflow execution in n8n’s UI to confirm no errors and proper email categorization.

Review Outlook inbox to verify emails are categorized and tagged with the appropriate importance.

For large inboxes, refine filters to control processing volume and avoid API rate limits.

9. FAQs

Q: Can I use Gmail instead of Microsoft Outlook with this workflow?
A: Technically yes, but node configurations for Gmail are different. Adapt filters and credentials accordingly.

Q: Does this workflow consume OpenAI API credits?
A: Yes, each email processed by GPT-4o consumes API tokens based on input length and model pricing.

Q: Is my email data secure?
A: Data flows through n8n and OpenAI securely via HTTPS. Ensure you use trusted API credentials and secure environments.

Q: Can this handle hundreds of emails daily?
A: Yes, but consider API rate limits and schedule the workflow accordingly for batch processing.

10. Conclusion

By following this guide, you’ve built a powerful AI email assistant that intelligently classifies and prioritizes Microsoft Outlook emails automatically. This workflow saves valuable hours weekly, reduces missed urgent emails, and streamlines your inbox management with precision AI guidance.

Consider extending this workflow by adding automated email responses, integrating further CRM data sources, or connecting to task management tools to close the loop on email-based tasks.

Embrace automation and let AI handle your inbox so you can focus on what truly matters!