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

What I Built

ReplyAs – a modern shared inbox platform that transforms how teams handle email collaboration. 📬 Instead of sharing passwords or forwarding emails, teams can now manage support emails together in real-time with complete transparency and control.
The platform features a unified inbox that multiple team members can access simultaneously, with live activity tracking to prevent duplicate responses and maintain email thread context. 🔄 Instead of replying to the same email from two different email addresses with different responses, team members can discuss among themselves and coordinate their approach before sending a unified reply.

The solution addresses the common pain point of teams needing shared email access without compromising security 🔐, making it perfect for customer support teams, shared department inboxes, or any collaborative email scenario. Teams can assign emails, add internal notes with @mentions, and track progress through a 5-stage workflow system (Todo → In Progress → Drafting Reply → In Review → Done). ✅

Demo🎬

🌐 Live Application

Try it yourself: replyas.com

• 📧 Email: postmarktest@replyas.com
• 🔑 Password: pass1234
• 🔗 Sign in at: https://replyas.com/auth/sign-in
• 📤 Send an email to postmarktest10@gmail.com
• 📥 Watch the reply appear in „support“ inbox
• 🎯 Explore other features in the app

Or, you can signup, feel free to create an account setup email forwarding try all the features.

Code Repository

How I Built It

🔧 Implementation Process

The building process was incredibly smooth thanks to Postmark’s inbound email parsing capabilities. The webhook integration was straightforward to implement, and the data structure provided by Postmark was well-organized and intuitive, making it easy to understand every field and its purpose.

🛠️ Tech Stack

• ⚡ Next.js with React 19
• 🎨 Shadcn/ui
• 🗄️ Supabase
• 🔄 Server Actions
• 🔍 TanStack Query
• 🛣️ Next.js API Routes for webhook handling and backend logic

How I Built It
I used a webhook endpoint to receive inbound emails from Postmark. The core implementation can be found in src/app/api/webhook/postmark/route.ts where I parse the structured email data, extract essential fields like Message-ID, sender information, and handle email threading through References and In-Reply-To headers.

Email Processing Workflow

Once I receive the finalEmailData from Postmark, my system handles several key operations:

1. Email Threading: I analyze the References and In-Reply-To headers to determine if this is a reply to an existing thread, then link it appropriately
2. Attachment Processing: Base64 attachments are decoded and saved with proper metadata handling
3. User Status Management: For each new email, I create individual status records for all team members (read/unread, bookmarked, subscribed status)
4. Spam & Filtering: Built-in spam detection and custom filtering rules are applied

After the initial save, everything else is handled seamlessly by my application logic. Postmark’s transactional email API was equally impressive – I created a simple wrapper function that made sending replies and notifications effortless.

The entire integration felt natural and well-documented, allowing me to focus on building the collaborative features rather than wrestling with email parsing complexities.

📦Key Features:

• 💬 Real-time internal chat for team coordination
• 🔔 @mentions and notifications to keep everyone in the loop
• 🎯 Intelligent filters that surface important emails instantly
• ⭐ Company-level features like starring and archiving for shared workflows
• 🔖 Personal-level features like bookmarks and quick access customization
• 📂 Filter views for archived emails, spam management, and organized categories
• 📧 Proper email rendering with full document, image, and embed support
• 🧵 Email thread creation maintaining reply chains and conversations
• 📊 Activity timeline showing what’s happening with each email
• 🌐 Custom domain integration with DNS verification
• 🔐 Role-based access control with admin and member permissions
• 🏗️ Self-hostable open-source architecture for complete data control

🚀 Upcoming Features / Future Improvements

• 🔐 Granular permissions for team members on per-inbox basis
• 👀 Custom „Views“ based on saved filters (e.g., „Starred and assigned to me“, „Received 10 days ago but not replied to“, „High value customer label and assigned to me“)
• 📎 Attachment support in the email reply editor

💡 Inspiration & Credits

• 📧 ProtonMail WebClient – For email rendering implementation