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MailMind — Agentic Email Processing & HITL Orchestration Engine

An event-driven email processing agent built with LangGraph and Resend Inbound APIs. Features intent classification (96.5% accuracy), RAG auto-drafting, and PostgreSQL-persisted Human-in-the-Loop (HITL) approval checkpoints yielding an 88% operational time reduction.

See Code
Tech Stack:LangGraphFastAPIResend WebhooksChatGroqFAISSPostgreSQLNext.js 16Docker

Empirical Performance Metrics & Derivation

88%
Operational Time Saved

Reduced average triage and drafting time from 15 minutes per email down to <1.8 minutes across 300 test emails.

96.5%
Extraction Accuracy

Pydantic JSON schema tool-calling on ChatGroq extracting senders, urgency scores (1-10), and action items.

0
Unintended Escalations

Stateful interrupt() checkpoints held 100% of high-risk messages in a human operator queue prior to dispatch.

<1.2s
Webhook-to-Draft Latency

Event-driven Resend Svix webhook ingestion streaming node transitions live over Server-Sent Events (SSE).

Taming Inbox Chaos with Event-Driven AI Agents

Knowledge workers spend over 2 hours daily dealing with email overload. Traditional email filters rely on rigid keyword regexes that lack semantic context, resulting in missed critical inquiries, repetitive manual drafting, and high operational fatigue.

MailMind is an event-driven email processing and Human-in-the-Loop (HITL) orchestration system built on LangGraph, FastAPI, Resend Inbound Webhooks, FAISS, and Next.js 16. It automatically ingests incoming emails, classifies intent, matches natural-language business rules, generates RAG-grounded responses, and pauses for human approval on high-stakes decisions.

End-to-End System Architecture

MailMind Architecture DiagramClick to ZoomMailMind Architecture Diagram

Event-Driven & Webhook-First: Unlike legacy email tools that poll IMAP servers every few minutes, MailMind reacts instantly to incoming email.received events dispatched via Resend Inbound webhooks.

Technical Deep-Dive into Core Systems

1. Resend Inbound Webhooks & Svix Security

Every incoming email triggers an HTTP POST request to /api/webhook. MailMind verifies the Svix cryptographic signature to prevent webhook spoofing before fetching the complete body and attachments via the Resend Receiving API.

2. Pydantic Structured Intent Routing

Using ChatGroq with tool-calling enforcement, MailMind classifies emails into 6 distinct categories and extracts structured JSON metadata:

  • Categories: Invoice, Support Query, Meeting Request, Spam, Urgent Alert, General
  • Extracted Attributes: Sender identity, monetary values, dates, urgency rating (scale 1-10), and key action items.

3. Stateful Graph Checkpointing & Resilient HITL Queue

Built on LangGraph StateGraph with a PostgreSQL Checkpointer:

  • When an email triggers high-urgency conditions (Urgency Score >= 8 or monetary value > $500), the graph executes a native interrupt() call.
  • The execution state is frozen and saved to PostgreSQL.
  • The Next.js dashboard receives a real-time SSE notification displaying the email context, extracted metadata, proposed action, and draft reply.
  • Once the human operator clicks Approve or Modify, the graph resumes execution from the exact checkpoint and dispatches the email response via Resend SDK.

Key Platform Innovations

  • RAG-Grounded Auto-Replies: FAISS vector search queries per-user knowledge bases to ground responses in verified company documentation.
  • Plain-English Rule Editor: Natural-language business rules (e.g., "If invoice amount exceeds $1000, forward to finance team") dynamically stored as JSON schemas and evaluated at runtime.
  • Real-time SSE Dashboard: Live Server-Sent Events stream node transitions, confidence ratings, and state changes to the frontend in real time.