Gmail Reply Classifier n8n: Gemini AI + Slack Routing

Automatically classify Gmail replies with Gemini and route next steps to Slack

This n8n workflow watches your Gmail inbox for labeled outreach replies, uses Google Gemini (PaLM) to classify each message and draft a suggested response, then logs everything to Google Sheets and alerts your team in Slack with a direct link to the saved draft.

What this workflow does

• Polls Gmail every minute when a new message arrives with your specified label (so replies can be separated from everything else).
• Fetches full email content and extracts the sender and subject.
• Cleans the reply body by removing quoted text, so Gemini classifies the actual new message.
• Sends the cleaned reply to Google Gemini to classify it into one of: Interested, Question, Objection, Not Interested, or Auto-Reply—and generates a suggested reply.
• Parses Gemini JSON output; if parsing fails, it falls back to Needs Manual Review.
• Appends results to Google Sheets, including email details, classification, confidence, reasoning, and the suggested reply.
• If the classification is Interested or Question, it creates a Gmail draft and posts a Slack alert linking directly to the draft.

Use cases

• SaaS teams qualifying outbound leads by quickly identifying replies worth responding to.
• Support or sales ops tracking outreach response sentiment in Google Sheets.
• Automation engineers routing high-priority conversations to Slack without manual sorting.

Technical details

• n8n Gmail Trigger (checks every minute for new labeled replies).
• Gmail node for fetching message content and saving draft replies.
• Google Gemini (PaLM) for classification + suggested reply generation.
• Google Sheets logging for classification, confidence, reasoning, and draft suggestion.
• Slack notification with a link to the saved Gmail draft.
• Uses nodes including if and code to parse Gemini output and handle the Needs Manual Review fallback.

Setup requires Gmail OAuth2, a Gmail label/filter for inbound replies (e.g., excluding from:me), a Gemini API credential, Google Sheets OAuth2 with mapped columns, and Slack OAuth2.