Automated Gmail Support Agent with Gemini 2.5, RAG & Cohere Reranking

Description

AI Email Support Agent with RAG & Cohere Reranking

Transform your inbox into an intelligent support system: automatically detect new emails, retrieve relevant knowledge from Pinecone, rerank with Cohere for precision, generate contextual replies using Gemini AI, and respond—all while maintaining conversation history.

What It Does

This workflow triggers on incoming Gmail messages, leverages a LangChain agent with PostgreSQL memory for context, queries a Pinecone vector store (RAG) enhanced by Cohere reranking and OpenAI embeddings, crafts personalized responses via Gemini 2.5, and auto-replies to keep support flowing.

Key Features

Gmail Integration** - Real-time polling for new emails every minute
RAG with Pinecone** - Retrieves top 10 relevant docs from "agency-info" index as agent tool
Cohere Reranking** - Boosts retrieval accuracy by reordering results semantically
Persistent Memory** - Postgres chat history keyed by email ID for ongoing threads
Gemini-Powered Agent** - Handles queries with custom system prompt for agency support
Seamless Auto-Reply** - Sends formatted text responses directly in Gmail

Perfect For

Agencies**: Automate client FAQs on services, pricing, and ownership
Support Teams**: Scale responses without losing conversation context
Small Businesses**: Handle inquiries 24/7 with AI-driven accuracy
Developers**: Prototype RAG agents with vector stores and rerankers
Marketers**: Personalize outreach replies based on knowledge base
Consultants**: Quick, informed answers from internal docs

Technical Highlights

Built on n8n's LangChain ecosystem, this workflow highlights:
Trigger-to-response pipeline with polling and webhooks
Hybrid retrieval: Embeddings + vector search + semantic reranking
Stateful agents with database-backed memory for multi-turn chats
Multi-provider setup: OpenAI (embeddings), Cohere (rerank), Google (LLM)
Scalable for production with configurable topK and session keys

Setup Instructions

Prerequisites
n8n instance with LangChain nodes enabled
Accounts for: Gmail (OAuth2), OpenAI (API key), Cohere (API key), Google Gemini (API key), Pinecone (API key and index), Postgres (database connection, e.g., Neon or Supabase)

Required Credentials
Gmail OAuth2
Enable Gmail API in Google Cloud Console
Create OAuth2 credential in n8n with scopes: https://www.googleapis.com/auth/gmail.readonly, https://www.googleapis.com/auth/gmail.send

OpenAI API
Get API key from platform.openai.com
Add as OpenAI credential in n8n

Cohere API
Sign up at cohere.com
Copy API key to n8n Cohere credential

Google Gemini API
Generate key at https://aistudio.google.com/
Add as Google PaLM credential in n8n (compatible with Gemini)

Pinecone API
Create index "agency-info" with dimension 1024
Add API key to n8n Pinecone credential

Postgres
Set up database (e.g., Neon/Supabase) with a table for chat history
Add connection details (host, database, user, password) to n8n Postgres credential

Configuration Steps
Import the workflow JSON into your n8n instance
Assign all required credentials to the respective nodes
Populate the Pinecone "agency-info" index with your knowledge base documents (use a separate upsert workflow or Pinecone dashboard)
Customize the tableName in the Postgres Memory node if needed (default: "email_support_agent_")
Adjust the agent's system prompt or topK retrieval if required for your use case
Activate the workflow and test by sending a sample email to trigger it

Troubleshooting
No trigger firing**: Verify Gmail scopes and polling interval
Empty retrieval**: Check Pinecone index population, dimensions (must be 1024), and document embeddings
Rerank errors**: Ensure Cohere API key is valid and has sufficient quota
Memory issues**: Confirm Postgres connection and that sessionKey uses email ID

Perfect for deploying hands-off email automation. Import, connect credentials, and activate!