For a desktop email client, the first results are pimalaya/himalaya, neomutt/neomutt (NeoMutt is a terminal-based email client that supports IMAP, POP3, multiple accounts, and PGP encryption, directly matching the request for a desktop email client, though it lacks calendar integration and push notifications) and foundry376/mailspring. nylas/nylas-mail and thundernest/k-9 round out the shortlist. Compare the match explanations and check the project documentation against your requirements.
Open-source desktop applications designed to manage and synchronize multiple email accounts within a single interface.
Himalaya is a command line email client and a suite of toolsets for email protocol implementation. It provides a terminal-based interface for managing email accounts using IMAP and SMTP protocols. The project includes a PIM framework and specialized libraries for building personal information management applications that integrate emails, contacts, calendars, and tasks. It features a PGP email encryptor for end-to-end encrypted communication and an email data exporter that extracts messages and metadata into JSON format for use in external scripts. The system covers a broad range of email ma
Himalaya is a terminal-based email client built in Rust that supports IMAP/SMTP, PGP encryption, and offline syncing, so it fits the core request for a desktop email client even though it lacks a graphical interface and some requested features like unified inbox, calendar integration, and push notifications.
NeoMutt is a terminal-based electronic mail management system that provides a text-based user interface for reading and composing emails. It functions as a mail manager and client supporting IMAP, POP3, and SMTP protocols, as well as NNTP for newsgroup access. The project distinguishes itself through integrated support for PGP and S/MIME encryption, providing tools for signing and encrypting messages and managing cryptographic keys. It supports modern authentication via OAuth2 and offers specialized MIME-aware reading capabilities for decoding multipart messages and visualizing MIME structure
NeoMutt is a terminal-based email client that supports IMAP, POP3, multiple accounts, and PGP encryption, directly matching the request for a desktop email client, though it lacks calendar integration and push notifications.
Mailspring is a cross-platform desktop email client designed to aggregate multiple accounts into a single, unified inbox. It utilizes standard protocols to synchronize messages and provides a centralized interface for managing professional correspondence across different email services. The application distinguishes itself through a suite of productivity tools that include automated message scheduling, follow-up reminders, and email engagement tracking to monitor recipient interactions. It also features contact enrichment to surface professional context and historical data, alongside built-in
Mailspring is a cross-platform desktop email client that unifies multiple accounts into a single inbox with IMAP support, search, and productivity tools, but it lacks explicit support for PGP encryption, offline mode, calendar integration, and push notifications, making it a good fit for the category though not a fully comprehensive option.
This project is a cross-platform desktop email client built with web technologies. It serves as an extensible mail application that allows users to manage and organize email correspondence and can link to self-hosted synchronization engines to manage user data. The application is designed for extensibility through a plugin architecture and logic extension hooks, enabling the addition of custom features such as text translation, email templating, and external service integrations. It further distinguishes itself by providing a customizable interface that supports user-defined CSS styling and t
Nylas Mail is a cross-platform desktop email client with support for multiple accounts and extensibility via plugins, but it may lack built-in PGP encryption, offline mode, and calendar integration out of the box, making it a narrower fit for your feature list.
K-9 is an open source email client for Android devices designed for sending and receiving electronic mail. It operates as an IMAP and SMTP mail client that allows users to synchronize and manage multiple email accounts. The application features a unified inbox that aggregates messages from various accounts into a single chronological view. This enables the organization of multiple mail sources within a centralized interface. The software handles mobile email management through local-first message storage for offline access and background service syncing to poll servers for new messages. It u
K-9 is an open-source email client for Android devices, not a desktop application, so it does not match the request for a desktop email client.
MailKit is a cross-platform .NET email protocol library used to implement IMAP, POP3, and SMTP functionality. It provides specialized client libraries for managing remote mailboxes, retrieving and downloading messages, and composing and transmitting emails to remote servers. The library supports secure identity verification through SASL authentication and OAuth 2.0 token-based flows. It includes capabilities for routing traffic through proxy gateways and decrypting PGP-encrypted content embedded within email bodies. The project covers a broad range of email operations, including folder manag
MailKit is a cross-platform .NET library for email protocols (IMAP, POP3, SMTP) and PGP decryption, but it is a development component for building email clients, not a ready-to-use desktop email client with a unified inbox, calendar, or push notifications.
Thunderbird for Android is a mobile email application designed to synchronize and organize messages from multiple providers within a single unified interface. It functions as an email client that manages accounts through standard network protocols, allowing users to consolidate personal, professional, and educational inboxes into one central location. The application distinguishes itself through integrated support for end-to-end privacy, utilizing cryptographic standards to encrypt and decrypt email content directly on the device. It maintains a local relational database for message storage,
This is a mobile email client for Android, not a desktop application, so it does not directly fit your search for a desktop email client.
Inbox Zero is an AI-powered email automation platform and inbox organizer. It uses large language models to automatically categorize, label, and archive emails, while providing a conversational interface for managing workflows and drafting responses through natural language. The project distinguishes itself by integrating real-time calendar availability into its drafting process and generating AI-summarized meeting briefings. It supports a pluggable AI provider interface with model fallback chains, allowing it to connect to various cloud or local LLM providers. Users can also control their in
Inbox Zero is an AI-powered email automation web app, not a desktop email client; it helps manage Gmail via APIs but lacks the core desktop-client features like multiple account support, offline mode, PGP encryption, and IMAP/POP3 connectivity.
| Repository | Stars | Language | License | Last push |
|---|---|---|---|---|
| pimalaya/himalaya | 6.5K | Rust | Apache-2.0 | |
| neomutt/neomutt | 3.7K | C | gpl-2.0 | |
| foundry376/mailspring |
| 17.6K |
| JavaScript |
| GPL-3.0 |
| nylas/nylas-mail | 24.7K | JavaScript | MIT |
| thundernest/k-9 | 13.6K | Kotlin | Apache-2.0 |
| jstedfast/mailkit | 6.8K | C# | MIT |
| thunderbird/thunderbird-android | 13.6K | Kotlin | Apache-2.0 |
| elie222/inbox-zero | 10.1K | TypeScript | other |