Mailspring Changelog

Features:

Company profiles are now available in the right sidebar! See tons of great information about the people you're emailing, including their local time zone, the company's core business area, and more.
You can now choose folder associations explicitly if Mailspring is unable to correctly identify your Sent folder, for example.
The IMAP/SMTP authentication panel automatically defaults to security settings that match the ports you provide.

Fixes:

Sending mail is considerably faster for accounts that do not place the message in the Sent folder automatically.
Sent mail no longer appears to be from Dec 31st 1969 when sent through some older SMTP gateways.
New folders / labels appear faster after you create them, and adding folders now works properly on IMAP servers that use a namespace prefix like INBOX..
Improves display of "Identity is missing required fields" error and directs people to a knowledge base article.
Localhost is an allowed IMAP/SMTP server address.
<object> tags are now completely blocked in message bodies.

Features:

You can now choose custom IMAP and SMTP ports when linking a custom email account.
You can now leave the SMTP username and password blank to connect to an SMTP gateway that does not require authentication.

Fixes:

On Linux, Mailspring looks for your trusted SSL certificate roots in more locations, fixing the "Certificate Errors" many Fedora and ArchLinux users were seeing when linking accounts.
On Linux, Mailspring bundles SASL2 and SASL2 plugins, resolving "Authentication Error" messages that users of non-Debian Linux distros saw when the local installation of SASL2 was an incompatible version.
On Linux, Mailspring now links against libsecret, resolving intermittent "Identity missing required fields" errors that were caused by the Node bindings to libgnome-keyring's API.
On Linux, composer and thread windows no longer have a "double window bar".
On Linux, window menu bars no longer hide until you press the Alt key.
The .rpm package now requires libXss, resolving installation issues for some users.
Spellchecking on linux now works reliably.
On Mac OS X, some menu shortcuts (like Command-H) now appear in the menu bar properly.
Mailspring now correctly parses mailto: links with multiple semicolon-separated CC and BCC addresses.
The "Raw HTML" signature editor is now the proper size.

Fixes:

During authentication, you can now view a "Raw Log" of the IMAP and SMTP communication with your servers for easy debugging of connection issues.
During authentication, Mailspring will warn you if you connect Gmail via IMAP.
The "Install Theme...", "Install a Plugin Manually..." and "Create a Plugin..." menu items now work. Note that Nylas Mail / N1 themes require some modifications to work with Mailspring!
On Windows and Linux, Mailspring can now make itself the default mail client.
The contact sidebar in the app now works reliably and is rate-limited for free users (The Clearbit API is very expensive!)
On Windows, Mailspring now displays emails with encoded subject lines (often containing emoji or foreign characters) correctly.
On Windows, you can now resize and maximize the Mailspring window.
Mailspring now skips folders it can't sync rather than stopping the entire account.

Fixes:

On Linux, Mailspring now syncs mail reliably thanks to fixed builds of curl and mailcore2.
On Windows, the app's icon now includes all the required resolutions.
Many other minor fixes and sync improvements.

Features:

Entirely re-written sync engine uses significantly less RAM and CPU, improving performance and battery life.
Mailspring launches 55% faster, thanks to a new package manager and theme manager and a thinner application bundle.
Improved quoted text detection makes it easier to read threads, especially messages sent from Exchange and older versions of Outlook.

Developer:

Mailspring now stores user preferences in the appropriate platform-specific location: Library/Application Support on the Mac, AppData/Roaming on Windows, etc.
NylasEnv is now known as AppEnv and nylas-exports and nylas-component-kit have been renamed mailspring-*. Additionally, packages need to specify "engines": {"mailspring":"*"} instead of listing nylas.
Much more of Mailspring has been converted to ES2016, and CoffeeScript is no longer supported for plugin development. The CoffeeScript interpreter will be removed in a future version. Please use ES2016 JavaScript instead.
Mailspring now uses Prettier — before submitting pull requests, ensure npm run lint is clean, or add a Prettier plugin to your text editor. (It's awesome!)
A plugin browser / "store" is coming soon - stay tuned!

Privacy:

Mailspring does not send your email credentials to the cloud. Features like Snooze, Send Later, and Send Reminders now run on your computer. Future versions may re-introduce the option to run these features in the cloud.