Mailspring is a new version of Nylas Mail maintained by one of the original authors. It's faster, leaner, and shipping today! It replaces the JavaScript sync code in Nylas Mail with a new C++ sync engine based on Mailcore2. It uses roughly half the RAM and CPU of Nylas Mail and idles with almost zero "CPU Wakes", which translates to great battery life. It also has an entirely revamped composer and other great new features.

Mailspring's UI is open source (GPLv3) and written in TypeScript with Electron and React - it's built on a plugin architecture and was designed to be easy to extend. Check out CONTRIBUTING.md to get started!

Mailspring's sync engine is spawned by the Electron application and runs locally on your computer. It is open source (GPLv3) and written in C++ and C. For convenience, however, when you set up your development environment, Mailspring uses the latest version of the sync engine we've shipped for your platform so you don't need to pull sources or install its compile-time dependencies.