Auto-Categorize Outlook Emails with AI in n8n

How It Works

1. Trigger: The workflow starts with the Microsoft Outlook Trigger node, polling your inbox every minute for new emails.

2. Extract & Clean Email Content: The email’s key fields (from, subject, isRead, body) are extracted. The body is converted from HTML to Markdown, then sanitized to plain text for reliable AI processing.

   Node Setup Details:

   • Microsoft Outlook Trigger

     • Resource: Message
     • Operation: Trigger on new email
     • Fields to Output: from, subject, isRead(optional), body
     • Folders to Include: (Set to your Inbox or specific folder IDs)

   • Markdown Node

     • Input: {{$json["body"]["content"]}} (HTML email body)
     • Output Key: Email Body Markdown
     • Purpose: Converts HTML to Markdown for easier downstream processing.

   • Sanitize Node (Code Node)

     • Input: Email Body Markdown from previous node

     • Purpose: Cleans up Markdown, strips images, links, HTML tags, table formatting, and truncates to 4000 characters.

     • Sample JS Code:

       // Get the markdown content from the previous node
       const markdownContent = $input.item.json["Email Body Markdown"];
       
       

3. Setup AI tools

   • Move message and Get Folders Outlook tools are required, get contacts is optional.
   • Set each field in the tools to "defined automatically by the model" and describe each field so the model understands how to use it.
   • OpenRouter or other LLM models tool: You can use any client for this, but make sure to use a model that does well with tool calls (Claude, GPT-4.1, Gemini 2.5 Pro, etc.).

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Best Practices & Notes

• AI Prompt Engineering: The AI is instructed to be conservative—never move emails from real people or saved contacts, and always explain its reasoning if it doesn’t move a message.
• This automation only works for NEW incoming messages.
• Inbox Zero: This system is designed to help you achieve and maintain Inbox Zero by keeping only actionable items in your main inbox.
• Customization: You can adjust the folder logic, add more categories, or tweak the AI prompt for your specific needs.
• Privacy: All processing happens within your n8n instance; no email data is stored outside your environment except for the AI call (which only receives sanitized, minimal content).