MimeKit is a mature, high-performance .NET library for creating, parsing, and manipulating MIME messages (email). It provides comprehensive support for all standard MIME structures (multipart, message/rfc822, content-transfer encodings), internationalized headers (RFC 2047/2231), and email security features including S/MIME, OpenPGP, DKIM, and ARC signing/verification. The library also includes a full HTML5 tokenizer, TNEF (Outlook Transport Neutral Encapsulation Format) reader, text format converters (HTML, flowed, plain), and a stream filter pipeline for encoding/decoding and line-ending normalization. The codebase is well-architected with clean abstractions (visitor pattern, filter chain, encoder/decoder interfaces), extensive unit tests, and benchmarks demonstrating 25x–75x faster parsing than competing .NET MIME libraries. It is distributed as NuGet packages (MimeKit, MimeKitLite) and is a .NET Foundation project. The repository also includes sample applications for Windows Forms, iOS, and Android, and a DKIM verifier sample.
Sup is a console-based email client written in Ruby, designed for heavy email users who prefer a keyboard-driven, terminal interface. It provides a Gmail-like workflow with thread-centric conversation view, labeling (tags), archiving, muting, and full-text search powered by Xapian. The application supports multiple local mail sources (mbox and Maildir), multiple accounts, and can be extended via Ruby hooks. It runs as a full-screen ncurses application with a buffer-based window manager, offering modes for inbox, search results, compose, reply, forward, and more. Architecturally, Sup follows a modular pattern with manager classes (PollManager, UpdateManager, UndoManager, DraftManager, etc.) that encapsulate state and behavior. The UI is built on a Mode hierarchy with a shared keymap DSL, allowing consistent keyboard navigation across different views. The core data flow involves polling mail sources, parsing messages with RMail, threading them using a JWZ-inspired algorithm, and indexing them into a Xapian database for fast search. Labels and state are persisted in YAML files and the Xapian index. Key entry points include the main `bin/sup` TUI, `bin/sup-sync` for index synchronization, `bin/sup-add` for adding sources, and various utility scripts. External dependencies include ncursesw, RMail, Xapian, GPGME, and Chronic for date parsing. The project is in maintenance mode, focusing on stability and bug fixes rather than new features, but remains actively maintained with CI across many Ruby versions.