n8n Gmail AI Labeling Workflow w/ Human Approval & OpenAI

Turn your Gmail inbox into an AI-assisted, human-approved labeling system—using n8n + OpenAI

This n8n Gmail AI Labeling Workflow w/ Human Approval & OpenAI samples emails from your inbox, uses OpenAI to propose a tailored set of Gmail labels and routing rules, and then requires human approval before any labels are created or messages are classified.

What this workflow does

• Starts from an n8n Form where you choose a sample size and a Gmail search window.
• Fetches a sample of recent inbox emails that match your search criteria, compacts fields like sender, subject, snippet, and existing labels for analysis.
• Uses OpenAI to propose label logic: it generates a proposed set of Gmail labels (with purposes and routing rules) based on the sampled emails.
• Routes to a review form so you can approve, reject, or optionally edit the proposed label names.
• Creates approved Gmail labels (and ensures a “Needs Review” label exists), then creates an “AI_Reviewed” label for deduplication.
• Classifies emails per approved labels: it retrieves inbox messages not marked AI_Reviewed, asks OpenAI to classify each email using only your approved labels, then:
  • applies the selected Gmail label
  • adds AI_Reviewed to prevent reprocessing
• Outputs a completion summary showing how many emails were labeled.

Use cases

• SaaS operators who want consistent Gmail categorization (e.g., invoices, support, sales leads) with oversight.
• Automation engineers testing AI-assisted workflows without letting the model create labels blindly.
• Teams migrating toward automated triage while maintaining a human approval step.

Technical details

• Integrations/Credentials: Gmail OAuth2 (read messages, manage labels) and OpenAI (label suggestion + per-email classification).
• n8n nodes/blocks mentioned: form, form trigger, gmail, code, if, and sticky note.
• Core behavior: sample → OpenAI label proposal → human review → create labels → classify only unprocessed emails (marked with AI_Reviewed).

Start setup by enabling n8n Forms, opening the provided “Start setup form” URL, and selecting your Gmail and OpenAI credentials in the relevant Gmail and OpenAI steps.