Now you can use the upstream Mailspring builds without signing in to Mailspring ID! To upgrade, install latest build from the official website, then open up the Subscription pane in settings and click Sign out. All your settings should stay in place.
This repo will stay up for historical purposes. Original README below.
💌 Mailspring Libre
Mailspring is a email client that is fast, free and beautiful. This Libre build comes with no telemetry at all, and is still filled with powerful features you will love, like Unified Inbox, Snooze, Send Later, Mail Rules, Templates and more!
N. B. Please note that Mailspring Libre build isn't fully open source right now: the sync engine, MailSync, is proprietary, and while we're working on replacing it, it probably won't happen anytime soon. By downloading Mailspring Libre build, you accept the MailSync license (which doesn't affect you as a regular user).
You can download compiled versions of Mailspring Libre build for Linux (deb and rpm), macOS (dmg and zip), and Windows (exe and msi) from GitHub Releases. There's also an AUR package maintained by @Panzki (thanks!). Unstable releases are available on Travis.
Our UI is entirely open-source and pull requests and contributions are welcome! There are a few ways to contribute: building a plugin, building a theme, improving translations, and submitting pull requests to the project itself.
Building A Plugin
Plugins lie at the heart of Mailspring and give it its powerful features. Building your own plugins allows you to integrate the app with other tools, experiment with new workflows, and more. Follow the Getting Started guide to write your first plugin in five minutes.
To create your own theme, check out the Mailspring-Theme-Starter.
To create your own plugin, check out the Mailspring-Plugin-Starter.
A plugin "store" like the Chrome Web Store is coming soon, and will make it easy for other users to discover plugins you create. (Right now, users need to "sideload" the plugins into the app by downloading them and copying them into place.)
You can share and browse Mailspring Plugins, and discuss plugin development with other developers, on our Discourse.
Building a Theme
The Mailspring user interface is styled using CSS, which means it's easy to modify and extend. Mailspring comes stock with a few beautiful themes, and there are many more which have been built by community developers. To start creating a theme, clone the theme starter!
You can share and browse Mailspring Themes, and discuss theme development with other developers, on our Discourse.
Localizing / Translating
Mailspring 1.5.0 and above support localization. If you're a fluent speaker of another language, we'd love your help improving translations. Check out the LOCALIZATION guide for more information.
Contributing to Mailspring Libre build
Pull requests are always welcome - check out CONTRIBUTING for more information about setting up the development environment, running tests locally, and submitting pull requests.