Herald is a terminal-native email and calendar application that provides a GUI-like workspace inside a modern terminal. It combines inbox reading, composing, search, cleanup tools, contacts, calendar handling, and optional AI-assisted features, while still offering keyboard-first navigation, mouse support, demo mode, and integration surfaces for MCP and SSH workflows.
This is source-available software. It is not open source.
Key Features
- Supports standard IMAP, Gmail IMAP app passwords, Gmail OAuth, SMTP, and provider presets for services such as ProtonMail Bridge, Fastmail, iCloud, and Outlook.
- Includes a calendar workspace with Google Calendar OAuth, CalDAV support, event management, RSVP handling, and .ics import.
- Offers a terminal UI with keyboard shortcuts, clickable tabs, mouse scrolling, OSC 8 email links, context help, and theme inheritance from the terminal.
- Provides inbox cleanup features including sender and domain grouping, dry-run cleanup previews, archiving, deleting, hiding senders, and unsubscribe actions.
- Adds optional AI features for classification, semantic search, quick replies, chat, contact enrichment, and draft assistance using Ollama or external providers.
Website: github.com/herald-email/herald-mail-app
Support:
Developer: Herald Email
License: Functional Source License 1.1, ALv2 Future License

Herald is written in Go. Learn Go with our recommended free books and free tutorials.
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