Mailspring 1.21.0

Mailspring is a fast, modern email client with unified inbox, powerful search, and productivity tools like snooze, templates, and tracking.

Razvan Serea News Reporter Neowin · May 6, 2026 22:00 EDT with 0 comments

MailSpring

Mailspring is a new version of Nylas Mail maintained by one of the original authors. It's faster, leaner, and shipping today! Mailspring supports all IMAP providers, including Gmail, Office 365 and iCloud. It sports features such as an unified inbox, snoozing, reminders, templates, offline search, and support for Gmail labels. Mailspring is free for Mac, Windows, and Linux. However, if you use features like Snooze, Send Later, Send Reminders and Read Receipts often, you'll need to purchase a subscription to Mailspring Pro within the app.

All of these features run in the client - Mailspring does not send your email credentials to the cloud.

Mailspring 1.21.0 changelog:

Features

Added Reply-To field to the composer header, allowing you to specify a different reply address when composing messages. (#2691) Thanks @Argjend12345!
Added bulk RFC2822 message export functionality to the sync engine. (#107)

Bug Fixes

Fixed HTTP/2 framing errors that could crash the sync engine during metadata streaming. (#103)
Prevented global keyboard shortcuts from firing when focus is in the composer. (#2693)
Strictly validate accent color hex values from system preferences to prevent errors. (#2692)

Claude Security Audit

Tightened validation to prevent file:// URIs in email content. (#2699)
Limited path traversal in protocol handler. (#2700)
Added allowlist validation for IPC window and webcontents methods. (#2701)
Improved HTML sanitization in the composer when pasting content. (#2702)
mailto links no longer support the ?attach= query parameter. (#2703)
Improved attachment name sanitization for security and compatibility. (#2705)
Improved email sanitization to block CSS @import tracking vectors. (#2706)
Added package name validation to prevent path traversal attacks. (#2698)
Added URL validation to the autoupdate handler. (#2697)
Show a notice about plugin trust when installing third-party plugins.

Improvements

When a detailed error log is available during OAuth sign-in, it is now displayed to help with troubleshooting.
Used exec in mailsync wrapper script for direct signal delivery. (#105)

Developer

Migrated build system from Grunt to a standalone Node.js script. (#2704)
Added option to skip installer creation in the build script. (#2707) Thanks @LinusDierheimer!
Dropped .map files from distribution packages. (#2686) Thanks @ReillyBrogan!
Replaced long-deprecated Raven with native Sentry envelope implementation and send sourcemaps during build. (#2694)
Upgraded TypeScript target from es2017 to es2024.
Refactored TypeScript compilation cache and only enable in dev mode. (#2695)
Removed macOS Touch Bar support. (#2696)
Updated ESLint and Prettier, and reference local versions in VS Code settings.
Added missing TypeScript types to function declarations across many files.
Upgraded Electron 41.2.1 to Electron 41.5.0.
Added Playwright tests for pre-release verification.
Added tests covering VCF/EML business logic and other utilities.