Papercut SMTP is a 2-in-1 quick email viewer AND built-in SMTP server (designed to receive messages only). Papercut SMTP doesn't enforce any restrictions how you prepare your email, but it allows you to view the whole email-chilada: body, html, headers, attachment down right down to the naughty raw encoded bits. Papercut can be configured to run on startup and sit quietly (minimized in the tray) only providing a notification when a new message has arrived.
Service Tray Manager - New Windows tray notification application for managing the Papercut SMTP Windows Service. Provides system tray icon with service status, start/stop/restart controls, quick access to the web UI, balloon notifications for new emails, and run-at-startup support. Fixes #249
Upgrade Dialog with Release Notes - When an update is available, a new dialog shows current vs. new version with rendered release notes so you can review changes before upgrading. Fixes #344
System Accent Color - Added a "System" option to the theme accent dropdown that reads and syncs with the Windows accent color in real-time. Now the default for new installs. Fixes #343
Web UI Overhaul - Completely refreshed the Papercut Service web interface:
Replaced Glyphicons with inline SVGs for a cleaner, dependency-free icon set
Per-message delete with confirmation via new DELETE /api/messages/{id} endpoint
Auto-refresh toggle button and browser back-button navigation
Modern visual design with Plus Jakarta Sans font, refined colors, and improved layout
Delete All Confirmation - "Delete All" now shows the message count and only deletes messages older than the confirmation timestamp, preventing accidental deletion of emails arriving during the confirmation dialog. Fixes #349 (Thanks, AntekOlszewski!)
Bug Fixes
FileSystemWatcher Reliability - Fixed emails silently stopping to appear in the UI. Root cause was FileSystemWatcher buffer overflows from excessive NotifyFilter events. Now uses FileName-only filter, 64KB buffer, auto-recreation on faults, and a 30-second periodic fallback refresh. Fixes #352
Notification Title - Fixed Windows toast notifications showing "velopack.PapercutSMTP" instead of "Papercut SMTP" by using Velopack's native --aumid flag at install time. Fixes #350
CID Embedded Images - Fixed intermittent failure to load Content-ID embedded images in the HTML viewer due to incorrect file:// URL format and MimeMessage cache state issues
HTML Email Preview (Web UI) - Fixed iframe collapsing to ~8px and load event race conditions by switching to $watch-based rendering with direct document writing, ResizeObserver support, and retry-based height measurement
Cross-Thread Theme Exception - Fixed crash when Windows system theme changes while the app is running
Improvements
Security: jQuery & Frontend Library Upgrades - Upgraded jQuery 1.11.0 to 3.7.1 and jQuery UI 1.10.4 to 1.14.1, mitigating CVE-2020-11022 and CVE-2020-11023 (XSS vulnerabilities). Also upgraded AngularJS 1.3.8 to 1.8.3 and Bootstrap 3.3.2 to 3.4.1. Fixes #353
Aspire Integration Documentation - Added documentation for using Papercut SMTP with .NET Aspire projects, including connection string format and setup examples. (Thanks, mguinness!)
Docker Documentation - Added troubleshooting guide for volume permission errors when running with mounted volumes
Dependencies - Updated NuGet packages and Velopack to v0.0.1521
Contributors
Special thanks to AntekOlszewski for fixing the Delete All race condition and mguinness for documenting Aspire integration!
Several features and fixes in this release were developed with the assistance of Claude Code.
