Postmark Challenge. Gentle Inbox

#devchallenge #postmarkchallenge #webdev #api

This is a submission for the Postmark Challenge: Inbox Innovators.

What I Built

Gentle Inbox - An AI-powered platform that transforms harsh customer feedback into constructive, professional communication while preserving all important information.

Business owners often receive brutal customer feedback that, while containing valid concerns, can be emotionally devastating and demoralizing. Gentle Inbox acts as an emotional buffer, using AI to rewrite harsh criticism in a gentler, more professional tone while maintaining every factual detail and legitimate concern.

Key Features:

Email-Based Feedback Collection: Customers send feedback to unique Postmark inbound addresses
AI-Powered Tone Transformation: OpenAI GPT-4o-mini rewrites harsh language professionally
Dual-View System: Business owners can toggle between original and softened versions
Real-Time Processing: Instant transformation and dashboard updates

The Problem It Solves:

Emotional Protection: Shields business owners from demoralizing feedback while preserving valuable insights
Improved Response Rates: Professional tone encourages constructive dialogue
Better Decision Making: Owners can focus on issues rather than emotional reactions
Mental Health: Reduces stress and anxiety from harsh customer communications

Demo

🔗 Live App: gentleinbox.com](https://gentleinbox.com/)

Testing Instructions:

Sign up for a free account at the demo link
Create your first business.

Copy your unique feedback email from the dashboard (format: feedback+[your-id]@gentleinbox.com)

Send harsh feedback to test the transformation:
- Try: "Your service is absolute garbage and you people are completely incompetent!"
- Watch it transform to: "I'm quite disappointed with the service quality and have experienced some significant issues."
View results in your dashboard with original/softened toggle

Test Credentials (if needed):

Demo Email: [email protected]
Password: PostmarkDemo2025

Code Repository

https://github.com/jburgoyn/gentle-inbox

Project Structure:

gentle-inbox/
├── frontend/          # React + Vite app
├── backend/           # Firebase Cloud Functions
├── firestore.rules    # Database security rules
└── README.md          # Setup and deployment guide

Key Technologies:

Frontend: React 18, Vite, Tailwind CSS, Firebase Auth
Backend: Firebase Cloud Functions, Firestore
APIs: Postmark Inbound Parsing, OpenAI GPT-4o-mini
Deployment: Firebase Hosting

How I Built It

Implementation Process

Designed system architecture with Postmark webhook → Cloud Function → AI processing → Real-time updates
Set up Firebase project with authentication, Firestore, and Cloud Functions
Configured Postmark inbound server with webhook endpoint
Built Postmark webhook handler to parse incoming emails and extract user IDs
Integrated OpenAI API with carefully crafted prompts to maintain customer perspective while softening tone
Created responsive React dashboard with Firebase Auth integration
Built original/softened toggle feature for transparency
Added sentiment analysis and basic analytics
Implemented comprehensive error handling and fallbacks

Tech Stack Deep Dive

Postmark Integration:

export const inboundEmailWebhook = onRequest(async (request, response) => {

    response.header("Content-Type", "application/json");
    response.header("Access-Control-Allow-Origin", "*");
    response.header("Access-Control-Allow-Headers", "Content-Type");

    corsHandler(request, response, async () => {

      const body = request.body; 
      // Extract businessId from email address (everything before @)
      const publicId = body.OriginalRecipient.split('@')[0].split('+')[1];

// Use that public id to fetch the user and business.
// Call the cloud function handleInboundEmail to transform the email

const functionUrl = `https://us-central1-gentle-inbox.cloudfunctions.net/handleInboundEmail`;

      const data = {
        business: business,
        body: body,
      }

      try {
         axios.post(functionUrl, data, {
          headers: {
            'Content-Type': 'application/json',
          }
        });
        logger.log("Successfully forwarded to handleInboundEmail");
      } catch (error) {
        logger.error("Error calling handleInboundEmail:", error);
      }

      return response.status(200).send();

    });
});

AI Transformation: The most challenging aspect was crafting prompts that consistently maintain the customer's perspective while softening harsh language. After extensive testing, I developed a comprehensive prompt system that:

Preserves all factual content and legitimate concerns
Removes personal attacks and profanity
Maintains appropriate urgency for serious issues
Uses professional, constructive language
Keeps the customer's voice and desired outcomes

Experience with Postmark

Postmark's inbound email parsing was incredibly developer-friendly. The JSON webhook format made it easy to extract all necessary information, and the documentation was clear and comprehensive. Key highlights:

Reliable Delivery: 100% webhook delivery success during development
Clean Data Format: Well-structured JSON with all email components
Flexible Addressing: Easy to implement user-specific email addresses
Great Documentation: Sample workflows made implementation straightforward

Challenges & Solutions

Challenge: Preventing AI from writing business responses instead of customer feedback transformation Solution: Extensive prompt engineering with specific examples and explicit constraints

Impact & Future Plans

Gentle Inbox addresses a real pain point for business owners, potentially improving mental health and response quality in customer service. Future enhancements could include:

Advanced sentiment analysis and trends
Industry-specific tone adjustments
Integration with popular CRM systems
Mobile app for on-the-go feedback management
Multi-language support

This project showcases Postmark's versatility beyond traditional transactional emails, demonstrating how inbound parsing can enable innovative communication solutions that genuinely improve people's work lives.

Built with ❤️ and lots of coffee during the Postmark Challenge. Special thanks to the Postmark team for creating such developer-friendly tools!