mu4e
What mu4e is
mu4e is a free, open-source email client for GNU Emacs on Linux desktops. Built on the mu search engine, it handles searching, reading, replying to, moving, and deleting Maildir messages. Its interface uses search queries instead of folder navigation, and it includes a unified inbox, offline access, and calendar tools. Common actions are designed for quick use, while heavier work runs asynchronously so Emacs remains responsive. Address completion can draw contacts from existing messages. Users can add custom actions and Emacs Lisp snippets. The manual documents signing, encryption, and decryption. Mail retrieval relies on Maildir updates from tools such as offlineimap, mbsync, or fetchmail; sending uses Emacs’s smtpmail package with the user’s SMTP provider. Integrations include Org-mode, desktop notifications, DBus, Dired, and iCalendar. mu4e is GPLv3 software in the mu source package on GitHub. Building its documentation requires Emacs 28 or later.
Who it suits
It suits Linux users who already work in GNU Emacs and manage Maildir email. It is useful for search-driven workflows and users wanting Emacs Lisp customization.
What it does well
- Free and GPLv3 licensed
- Search-based Maildir workflow
- Unified inbox and offline access
- Supports message encryption
- Extensible with Emacs Lisp
What to know first
- Linux desktop focus
- Requires GNU Emacs
- Requires mu and Maildir
- Mail retrieval needs external tools
Plans
| Plan | Billed and limits | Price |
|---|---|---|
| mu4e | GNU Emacs email client · GPLv3 · requires mu and Maildir | Free |
As djcbsoftware.nl lists them, read 12 Oct 2026. The maker's own page has the final word.
Verdict
mu4e brings search-centered email management into GNU Emacs, with offline use and extensive integration options. Setup depends on Emacs, mu, Maildir, and separate retrieval and SMTP tools.
Facts from mu4e's own pages
- App coverage
- desktop · djcbsoftware.nl, 20 Sept 2026
- Calendar tools
- Yes · djcbsoftware.nl, 20 Sept 2026
- Contacts
- Address auto-completion uses contacts found in the user's messages. · djcbsoftware.nl, 12 Oct 2026
- Customization
- Users can extend mu4e with custom actions and their own Emacs Lisp snippets. · djcbsoftware.nl, 12 Oct 2026
- Download
- mu4e is included in the mu source package, which is available from GitHub; some Linux distributions provide pre-built mu packages. · djcbsoftware.nl, 12 Oct 2026
- Encryption and signing
- The manual lists support for signing, encrypting, and decrypting messages. · djcbsoftware.nl, 12 Oct 2026
- Integrations
- The manual documents integration with Emacs facilities including Org-mode, desktop notifications, DBus, Dired, and iCalendar. · djcbsoftware.nl, 12 Oct 2026
- License
- mu4e is Free Software licensed under the GNU GPLv3. · djcbsoftware.nl, 12 Oct 2026
- Mail retrieval
- mu4e works on a Maildir that can be updated by tools such as offlineimap, mbsync, or fetchmail. · djcbsoftware.nl, 12 Oct 2026
- Offline access
- Yes · djcbsoftware.nl, 20 Sept 2026
- Platform limitation
- The mu project's Windows support is described as experimental and not supportable by its maintainers due to lack of specific expertise. · github.com, 12 Oct 2026
- Requirements
- The mu project installation instructions say mu4e requires Emacs version 28 or later to build its documentation. · github.com, 12 Oct 2026
- Search
- The interface is search-based, using queries instead of folders. · djcbsoftware.nl, 12 Oct 2026
- Sending mail
- Sending mail uses Emacs's smtpmail package, configured for the user's SMTP provider. · github.com, 12 Oct 2026
- Speed
- The interface is optimized for quick common actions, and heavy actions run asynchronously so they do not block Emacs. · djcbsoftware.nl, 12 Oct 2026
- Support
- The project directs bug reports and feature requests to its issue tracker and provides a mu-discuss mailing list. · djcbsoftware.nl, 12 Oct 2026
- Unified inbox
- Yes · djcbsoftware.nl, 20 Sept 2026
- What it does
- mu4e is an email client for GNU Emacs, built on the mu email search engine, for searching, reading, replying to, moving, and deleting Maildir messages. · djcbsoftware.nl, 12 Oct 2026
Where mu4e stands on Freedom251
- Email clients#106 of 142