mu4e

EmacsEmail client

Email client that runs inside GNU Emacs, built on the mu Maildir indexer and search tool.

mu4e reads mail from a local Maildir that mu indexes with Xapian, and its views are search queries rather than folders. Mail is fetched by a separate program such as mbsync (isync), and sent through Emacs smtpmail or an external sendmail-compatible program. It reuses the Gnus message and article modes, so signing, encryption and HTML rendering come from Emacs. It suits Emacs users who keep mail offline and want fast full-text search.

Type: Email client
Interface: Runs inside Emacs
Systems: Runs on Linux, macOS and BSD, on Windows through WSL, on Android through Termux.
Language: Emacs Lisp (mu4e), C++ (mu)
License: GPL 3.0 or later
Latest version: 1.14.3
Background: Emacs front end of the mu project
Maintained: Yes
Website: djcbsoftware.nl
Source: github.com/djcb/mu
Documentation: djcbsoftware.nl

Install

System	Support	Install
Linux	Native	apt`sudo apt install mu4e isync` dnf`sudo dnf install maildir-utils isync emacs` AUR`yay -S mu isync`
macOS	Native	Homebrew`brew install mu isync emacs`
Windows	Through WSL	WSL`sudo apt install mu4e isync` mu has no Windows package and upstream calls native Windows support experimental; run Emacs, mu and mbsync in WSL.
BSD	Native	FreeBSD pkg`pkg install mu isync` OpenBSD`pkg_add mu isync`
Android	Through Termux	Termux`pkg install mu isync`

Protocols and features

Protocols
Protocol	mu4e
IMAP	Through a separate tool
POP3	Through a separate tool
SMTP	Yes
JMAP	No
Maildir	Yes
mbox	No
notmuch	No

Features
Feature	mu4e
OpenPGP	Yes
S/MIME	via Emacs MML
OAuth2 sign-in	via script
Threads	Yes
Search	Xapian full-text index with mu query syntax
HTML mail	built-in, rendered with the Emacs shr library
Mouse	Yes
Multiple accounts	via contexts
Offline use	full; reads a local Maildir synced by mbsync or OfflineIMAP
Calendar	replies to invitations with mu4e-icalendar
Contacts	address completion from indexed mail
Vim-style keys	No
Configuration	Emacs Lisp in init.el

Pros and cons

Pros

Full-text search over all local mail through mu's Xapian index.
Works offline, since all mail lives in a local Maildir.
Uses Emacs message mode, so PGP/MIME, S/MIME and Org mode links are available.

Cons

No built-in IMAP; needs mbsync or a similar sync tool, so setup spans several config files.
Requires Emacs and some Emacs Lisp to configure.
No native Windows build, and Arch packages it only in the AUR.

Use mu4e with Forward Email

A working setup for a Forward Email mailbox. Replace you@example.com with your alias and the password command with your own. The same settings work with any provider once the server names change.

~/.mbsyncrc and ~/.emacs.d/init.el

# 1) ~/.mbsyncrc: sync the mailbox to ~/Mail/forwardemail (isync 1.5+ syntax)
IMAPAccount forwardemail
Host imap.forwardemail.net
Port 993
User you@example.com
PassCmd "pass show email/forwardemail"
TLSType IMAPS

IMAPStore forwardemail-remote
Account forwardemail

MaildirStore forwardemail-local
SubFolders Verbatim
Path ~/Mail/forwardemail/
Inbox ~/Mail/forwardemail/INBOX

Channel forwardemail
Far :forwardemail-remote:
Near :forwardemail-local:
Patterns * !Drafts
Create Both
Expunge Both
SyncState *

# 2) First sync and index:
#    mbsync forwardemail
#    mu init --maildir=~/Mail --personal-address=you@example.com && mu index

# 3) ~/.emacs.d/init.el
(require 'mu4e)
(setq user-mail-address "you@example.com"
      user-full-name "Your Name"
      mu4e-get-mail-command "mbsync forwardemail"
      mu4e-change-filenames-when-moving t
      mu4e-sent-folder "/forwardemail/Sent Mail"
      mu4e-drafts-folder "/forwardemail/Drafts"
      mu4e-trash-folder "/forwardemail/Trash"
      message-send-mail-function 'smtpmail-send-it
      smtpmail-smtp-server "smtp.forwardemail.net"
      smtpmail-smtp-service 465
      smtpmail-stream-type 'ssl
      smtpmail-smtp-user "you@example.com")

# 4) SMTP password in ~/.authinfo.gpg (read by Emacs auth-source):
# machine smtp.forwardemail.net login you@example.com port 465 password YOUR-GENERATED-PASSWORD

Protocol	Server	Port	Security
IMAP	`imap.forwardemail.net`	993	SSL/TLS
POP3	`pop3.forwardemail.net`	995	SSL/TLS
SMTP	`smtp.forwardemail.net`	465	SSL/TLS
SMTP	`smtp.forwardemail.net`	587	STARTTLS

Username: your full alias address, such as you@example.com. Password: the one shown by Generate Password next to the alias in your Forward Email account. Folders: INBOX, Drafts, Sent Mail, Trash, Spam and Archive.

Prefer no config at all? Forward Email's terminal app signs in with your account and has mail, calendar and contacts in one program.

Compare mu4e

All mu4e alternatives

Questions

Does mu4e work on Windows?

Not natively. It runs in Windows Subsystem for Linux (WSL). mu has no Windows package and upstream calls native Windows support experimental; run Emacs, mu and mbsync in WSL.

Does mu4e support IMAP?

Through a separate tool. mu4e reads local mail, so a sync program such as isync copies it from the IMAP server.

Is mu4e open source?

Yes, under the GPL 3.0 or later.

How do I use mu4e with Forward Email?

Use the config in the Forward Email section on this page, saved as ~/.mbsyncrc and ~/.emacs.d/init.el, and replace the address and password with your own.

Sources

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