In my continuing investigation of Emacs, I'm experimenting with checking email locally (i.e. on my computer) rather than using a web browser. I've used Gmail's web interface for my email for probably eight years at this point. Several years ago my friend recommended checking out notmuch for email; I poked around with it at the time but didn't understand what I was doing. Here's what I've figured out in trying to set this up again.

1. Concepts

Where we're going is:

  1. gmi (gmailieer) is going to check gmail, both pulling messages and synchronizing labels/tags
  2. notmuch is going to own the local machine's email indexing/tagging
  3. The Notmuch Emacs interface is going to own the actual MUA (mail user agent) work such as finding and reading emails
  4. Emacs's message-mode will be used to send emails

2. Failed attempts

I tried to use offlineimap for this first. However, (a) I didn't know what I was doing at all and (b) getting Gmail's labels to align to notmuch's labels required lots of nametrans and folderfilter lambda functions.

3. Shell work

Before Emacs is involved, a bunch of applications have to be installed and configured. First, notmuch and gmailieer have to be installed.

These instructions are OS X+Macports specific, but hopefully they are easy to understand and adapt to other platforms. These instructions also assume you have python-3.6, virtualenv, and virtualenvwrapper installed and virtualenvwrapper has been sourced in your current shell (i.e. you are actually using virtualenvwrapper). 

# Make sure notmuch is installed:
sudo port install notmuch
cat > ~/.notmuch-config <<EOF
[database]
path=~/Mail
[user]
name=John Borwick
primary_email=john_borwick@pobox.com
[new]
tags=new
ignore=
[search]
exclude_tags=deleted;spam;
[maildir]
synchronize_flags=true
[crypto]
gpg_path=gpg
EOF
# Create & then use virtualenv. (mkvirtualenv does this)
mkvirtualenv --python=python3.6 gmailieer
mkdir -p ~/build
cd ~/build
# install notmuch libraries. ideally this would be from the same
# notmuch source as the above, but this works:
git clone https://git.notmuchmail.org/git/notmuch
cd notmuch/bindings/python
python setup.py install
  # install gmailieer:
cd ~/build
git clone https://github.com/gauteh/gmailieer.git
cd gmailieer
python setup.py install
# create notmuch database:
mkdir ~/Mail
cd ~/Mail
notmuch new
# ... ideally get a Google developer API certificate and call
#  gmi auth -c your-client-secrets.json
gmi init
# This changes gmi to pull the "promotions", "updates", etc tags:
gmi set --ignore-tags-remote ""
# This is the step that takes forever:
gmi pull
# make notmuch call gmi when 'notmuch new' is called:
mkdir -p .notmuch/hooks
cat > .notmuch/hooks/pre-new <<EOF
#!/bin/sh
source ~/.virtualenvs/gmailieer/bin/activate
cd ~/Mail
gmi sync
EOF
chmod +x .notmuch/hooks/pre-new

If all goes well, gmi pull will show a progress bar and when done, your gmail email will be on your computer with the same labels (notmuch "tags") that you have in gmail.

4. Emacs setup

The other big step is configuring Emacs. Here's what I've done, all in my ~/.emacs.d/init.el: 

; If I'm going to send email then I would like address completion. Therefore I'm going to
; use Big Brother database, for contacts:
(when (not (require 'bbdb nil t))
   	   (package-refresh-contents)
	   (package-install 'bbdb))
; Notmuch for Emacs:
(when (not (require 'notmuch nil t))
   	   (package-refresh-contents)
	   (package-install 'notmuch))
; want org-plus-contrib to get org-notmuch:
(add-to-list 'package-archives '("org" . "http://orgmode.org/elpa/") t)
(when (not (require 'org-plus-contrib nil t))
           (package-refresh-contents)
           (package-install 'org-plus-contrib))
(require 'bbdb)
(require 'org-notmuch)

; configure outgoing SMTP (so you can send messages):
(setq smtpmail-smtp-server "smtp.gmail.com"
      smtpmail-smtp-service 587)

I wouldn't be surprised if there are other things missing from the above, but I think that's most of the config. Once everything is set up, you should be able to run M-x notmuch.

Within notmuch, G calls notmuch new, which due to the pre-new script in Shell work, above, will call gmi sync to receive new mail and send any label changes.

5. Next steps

I've begun to build my notmuch-specific tags: 

cd ~/Mail
cat > .notmuch/hooks/post-new <<EOF
#!/bin/sh
notmuch tag +to_me -- to:john_borwick@pobox.com and -tag:to_me
notmuch tag +to_me -- to:my-other-email@example.com and -tag:to_me
EOF
chmod +x ~/.notmuch/hooks/post-new

# Run this script for the first time:
.notmuch/hooks/post-new
# Synchronize these new labels with gmail:
gmi sync

The post-new script can be used to add other tags. Also, the above configuration gives every message a notmuch new tag (that isn't synchronized to Google); you can add that tag to your logic if you only want to parse emails that have recently come in. You can also add other labels (such as this to_me label) to your local labels to ignore; please check the gmailieer documentation on how to do this.

Updated: