Mailgorithm — Email-Based Tiny Cryptography Lessons

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

What I Built

Mailgorithm is an interactive email-based cryptography learning platform that transforms your inbox into a micro classroom. It delivers 12 bite-sized lessons on cryptography through engaging email exchanges using Postmark's inbound email parsing capabilities.

Students learn by solving puzzles, decoding secret messages, and replying with answers, directly through email. The platform covers fundamentals from ancient Caesar ciphers to modern post-quantum cryptography, making complex security concepts accessible through gamified, hands-on learning. Each lesson builds on the previous one, and students can compete on a real-time leaderboard tracking the fastest completion times.

What makes Mailgorithm truly unique is that email isn't just the delivery method, it's the entire user interface. The learning experience takes place entirely through email, making the medium perfectly match the message.

Beyond education, Mailgorithm hints at a complete evolution of the classic newsletter system. Instead of one-way broadcasts, users reply to emails, and their answers—parsed through Postmark's inbound stream trigger the next email. This transforms the email experience from passive reading to active participation. Even more exciting, the logic can be expanded to support dozens of branching paths and email responses based on user replies, enabling personalized, interactive, and dynamic email journeys.

Demo

• Live Application: Mailgorithm

Testing Instructions:

1. Visit the website and enter any valid email address
2. Check your inbox for the first cryptography lesson
3. Read the lesson and reply with the answer word
4. Continue receiving and solving lessons via email
5. If stuck, reply with "answer" to any lesson for an explanation
6. At the end of the course, track your progress on the public leaderboard

Code Repository

• Repository: GitHub

How I Built It

The project is built using Node.js with Express for the backend API, PostgreSQL with Prisma ORM for tracking user progress, and Docker for deployment.

The standout feature is the innovative use of Postmark, not just for transactional emails, but as the core interaction via inbound email parsing. Postmark webhooks validate user answers and trigger progression through the course by sending the next email.

The course starts with foundational cryptographic concepts and advancing to cutting-edge topics like post-quantum cryptography. Each lesson includes historical insights, hands-on examples, and tiny interactive puzzles.

Instead of a conventional web app, I opted for an email-first approach. The entire learning experience lives in your inbox: you learn by replying directly to the lessons.