Configuring Doom emacs, mbsync, and mu4e for use with o365

One of these days, this blog will be used for more than just notes to myself again.


For the past year, I have been enraptured with Emacs. I’ve embraced the idea of extending it into as many facets of my workflow as possible. This post details how I was able to get my work email setup in mu4e for easy task creation via org-mode.

For several years, I’ve been using my inbox as a todo list, filing email into a complex folder hierarchy. Once I discovered org-mode, I realized that I should use email as an interface for correspondence only. If a message came in that I should act on at some future point, it should be captured in my org todo and then discarded. I believe this follows in the principles of GTD.

I’m using:


mbsync is a mailbox synchronizer that retrieves messages via IMAP from a remote mailstore and saves them as flat files locally.

mbsync Configuration

mbsync configuration is performed in ~/.mbsyncrc (and in fact requires this file to run). Here’s my ~/.mbsyncrc:

IMAPAccount work
User [email protected]
PassCmd "security find-generic-password -s NoMAD -w"
SSLVersion TLSv1.2
AuthMechs PLAIN
# Increase timeout to avoid o365 IMAP hiccups
Timeout 120
PipelineDepth 50

IMAPStore work-remote
Account work

MaildirStore work-local
# Note the trailing slash on the Path statement!
Path ~/.mail/work/
Inbox ~/.mail/work/Inbox
SubFolders Legacy

Channel work
Master :work-remote:
Slave :work-local:
#Include everything
Patterns *
# Sync changes (creations/deletions) with the server
Create Both
Expunge Both
Sync All

Verify mbsync is working correctly with $ mbsync work. This will pull down work mail to ~/.mail/work/ with a folder layout mimicking Exchange’s mail folder structure.

Some items to note:

  • Create Both and Expunge Both means mbsync can delete messages on your mailserver. If you want to try this configuration out in read-only mode, set these values to Create Slave and Expunge Slave instead.
  • The trailing slash on the local MaildirStore path statement is critical!
  • My experience with Exchange 365 has been chaotic. I’ve set a Timeout 120 value to try to ensure there are no sync hiccups. This value has proved useful to me, but you can change it or remove it as you see fit.
  • mbsync will not delete mail folders on the server. Before you use this tool, it might be wise to ensure your Exchange folder hierarchy is as flat as possible. This can be done using the Outlook or OWA client.
  • PassCmd allows you to retrieve credentials from a CLI password manager tool

Now email can be synced and retrieved from the mailserver.


mu is a command-line mail client that provides superior mail search capabilities. Installing this package will automatically pull down mu4e (mu 4 Emacs) as well.

mu4e Prerequisites

On macOS, install mu (which includes mu4e) and mbsync. Note that mbsync is part of the isync homebrew collection. These are both installed in the terminal using homebrew:

brew install mu
brew install isync

Installing from homebrew should place the required files in /usr/local/share/emacs/site-lisp/mu/mu4e that will be loaded in the configuration below.

Run mu

Before using mu4e it’s a good idea to verify that mu works as expected, after all, mu4e uses mu as its engine.

To validate, mu must first create a mail index. Run:

$ mu index --maildir=~/.mail/work

Once this completes, give mu a spin:

$ mu find timecard

$ mu find from:myboss

At this point, mail is synced, indexed, and searchable from Exchange.

Doom Emacs

I am thoroughly impresed with Doom Emacs, and use it as my base. Configuring this distribution is slightly different from configuring mu4e in vanilla Emacs.

First, security:

Securely Store SMTP Credentials

SMTP is used to transfer outbound messages. I store my o365 creds in a gpg-encrypted file, ~/.emacs.d/.authinfo.gpg

Create authinfo file

Enter the credentials for the SMTP server in ~/.authinfo using the format:

machine login myusername port 587 password mypassword

Use quotes to contain the password, for instance:

machine login [email protected] password "mypassword" port 587

Encrypt authinfo file

Use gpg to encrypt the authinfo file. (macOS users, install This will place a symlink to the gpg CLI tool in your /usr/local/bin so make sure that’s in your shell’s $PATH.

I won’t cover the process of creating a keypair in this article, but you can find more information here and here.

Find the gpg key you want to encrypt this file with using $ gpg --list-keys:

pub   rsa4096 2019-01-22 [SC] [expires: 2023-01-22]
uid           [ultimate] Chris Lockard <[email protected]>
sub   rsa4096 2019-01-22 [E] [expires: 2023-01-22]
sub   rsa4096 2019-09-09 [S] [expires: 2023-09-08]
sub   rsa4096 2019-09-09 [E] [expires: 2023-09-08]
sub   rsa4096 2019-09-09 [A] [expires: 2023-09-08]

Now encrypt ~/.authinfo using the following:

$ gpg -se ~/.authinfo

This prompts for the key to use, so either enter [email protected] or the key signature - A9A79C3D5. The output of this program is an encrypted file, ~/.authinfo.gpg. For added security, set the permissions on this file to chmod 600 ~/.authinfo.gpg.

Finally, move this file with mv .authinfo.gpg ~/.emacs.d and cleanup the file containing cleartext credentials with rm .authinfo. Emacs will automatically know to look for ~/.emacs.d/authinfo.gpg which will help later when configuring SMTP.

Doom Emacs Configuration

I store my Doom configuration files in my github and link them thusly:

ln -s ~/Documents/dotfiles/Emacs/.doom.d ~/.doom.d

Doom defines packages in ~/.doom.d/init.el with user configuration in ~/.doom.d/config.el (or for literate config-ers like me :))


As mu4e is a package only available on the local filesystem, Doom needs to know from where to load it. The following line is added at the top of the file:

;; enabled and in what order they will be loaded. Remember to run 'doom refresh'
;; after modifying it.
;; More information about these modules (and what flags they support) can be
;; found in modules/

;; This is needed because emacs won't pick up mu4e otherwise:
(add-to-list 'load-path "/usr/local/share/emacs/site-lisp/mu/mu4e/")
(doom! :input


This mu4e path is where Homebrew installed mu4e (from the mu package) by default on macOS Mojave.

Further down init.el, uncomment mu4e from the :email block:

       mu4e       ; WIP


mu4e configuration is placed in or config.el. Mine looks like this:

(after! mu4e
  (setq! mu4e-maildir (expand-file-name "~/.mail/work") ; the rest of the mu4e folders are RELATIVE to this one
         mu4e-get-mail-command "mbsync -a"
         mu4e-index-update-in-background t
         mu4e-compose-signature-auto-include t
         mu4e-use-fancy-chars t
         mu4e-view-show-addresses t
         mu4e-view-show-images t
         mu4e-compose-format-flowed t
         ;mu4e-compose-in-new-frame t
         mu4e-change-filenames-when-moving t ;;
         '( ("/Inbox" . ?i)
            ("/Archive" . ?a)
            ("/Drafts" . ?d)
            ("/Deleted Items" . ?t)
            ("/Sent Items" . ?s))

         ;; Message Formatting and sending
         message-send-mail-function 'smtpmail-send-it
         message-signature-file "~/Documents/dotfiles/Emacs/.doom.d/.mailsignature"
         message-citation-line-format "On %a %d %b %Y at %R, %f wrote:\n"
         message-citation-line-function 'message-insert-formatted-citation-line
         message-kill-buffer-on-exit t

         ;; Org mu4e
         org-mu4e-convert-to-html t
(set-email-account! "[email protected]"
                    '((user-mail-address      . "[email protected]")
                      (user-full-name         . "Chris Lockard")
                      (smtpmail-smtp-server   . "")
                      (smtpmail-smtp-service  . 587)
                      (smtpmail-stream-type   . starttls)
                      (smtpmail-debug-info    . t)
                      (mu4e-drafts-folder     . "/Drafts")
                      (mu4e-refile-folder     . "/Archive")
                      (mu4e-sent-folder       . "/Sent Items")
                      (mu4e-trash-folder      . "/Deleted Items")
                      (mu4e-update-interval   . 1800)
                      ;(mu4e-sent-messages-behavior . 'delete)


Everything is in place to use Doom Emacs as a mail client!

Start Emacs and run M-x mu4e:

Doom mu4e

Compose a message

Press C to bring up the message composition window:

Compose message

To send a message, place the cursor in the header section (gg <ESC>) and then SPC m s. You’ll be prompted to enter the passphrase for your gpg key (sometimes twice) and then your message will send once Emacs decrypts your ~/.emacs.d/authinfo.gpg to retrieve SMTP credentials.

Reply to a message

From the inbox view, press R to reply to a message. Fill out your response, then send the message by again placing point in the message header section (gg <ESC>) and then SPC m s.

Capture a message as a task in orgmode

From the inbox view, select a message with <Enter> to open the message view. With point in the header section (it should be there by default) and press SPC X or M-x org-capture. With an appropriate capture template, this message will be linked into org mode for use in your GTD workflow.


This specific configuration required referencing many resources. I’ve included these below:

Doom Emacs configurations:

Mbsync configurations:

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