Switching to the Mutt Email Client

Note: The way I manage my email wouldn’t really work for most people, so don’t read this as a recommendation. This is just a discussion of how I prefer to use email.

It was almost four years ago I switched from webmail to a customized email configuration based on Notmuch and Emacs. Notmuch served as both as a native back-end that provided indexing and tagging, as well as a front-end, written in Emacs Lisp. It dramatically improved my email experience, and I wished I had done it earlier. I’ve really enjoyed having so much direct control over my email.

However, I’m always fiddling with things — fiddling feels a lot more productive than it actually is — and last month I re-invented my email situation, this time switching to a combination of Mutt, Vim, mu, and tmux. The entirety of my email interface now resides inside a terminal, and I’m enjoying it even more. I feel I’ve “leveled up” again in my email habits.

On the server-side I also switched from Exim to Postfix and procmail, making the server configuration a whole lot simpler. Including SpamAssassin, it’s just three lines added to the default Debian configuration. It leaves a lot less room for error, and I could rebuild it from scratch with little trouble if there was an emergency. My previous configuration required quite a bit of system configuration, such as relying on incron to sort incoming mail, particularly spam, but procmail now does this job more cleanly.

Towards Robustness

Over the years I’ve gotten less patient when it comes to dealing with breaking changes in software, and I’ve gotten more conservative about system stability. Continuously updating my configurations and habits to the latest software changes was an interesting challenge earlier in my career, but today there are much better uses of my time. Debian Stable, my preferred operating system, runs at pretty much the perfect pace for me.

Following these changing preferences, one of the biggest motivations for my recent email change was to make my email setup more robust and stable. Until now, email was tied tightly to Emacs, with a configuration drawing directly from MELPA, pulling in the bleeding edge version of every package I use. Breaking changes arrive at unexpected times, and occasionally the current version of a package temporarily doesn’t work. Usually it’s because the developer pushed a bad commit right before the latest MELPA build, and so the package is broken for a few hours or days. I’ve been guilty of this myself. MELPA Stable is intended to address these issues, but it seems to break more often than normal MELPA. For example, at the time of this writing, Evil is not installable via MELPA Stable due to an unmet dependency.

Tying something as vital as email to this Rube Goldberg machine made me nervous. Access to my email depended on a number of independent systems of various levels of stability to mostly work correctly. My switch to Mutt cut this down to just a couple of very stable systems.


I’ve long believed HTML email is an abomination that should never have been invented. Text is the ideal format for email, and there are a number of specifications to make it work well across different systems. One of those standards is RFC 3676, colloquially named format=flowed, or just f=f.

Messages encoded with f=f allow mail clients to safely reflow the paragraphs to nicely fit the user’s display, whether that display be thinner or wider than the sender’s original message. It’s also completely compatible with mail clients that don’t understand format=flowed, which will display the message as the sender originally wrapped it.

The gist of f=f is that messages can have both “soft” and “hard” line breaks. If a line ends with a space, then it’s a soft line break. The mail client can safely reflow lines separated by a soft line break. Without the trailing space, it’s a hard line break, which prohibits flowing with the next line. The last line of a paragraph ends with a hard line break. It’s also used for text that shouldn’t reflow, such as code samples.

I’ll illustrate using an underscore in place of a space, so that you can see it:

This is a message in the format=flowed style, allowing_
mail clients to flow this message nicely in displays of_
different widths.

> This is an example of a quote block in a message,_
> which is supported by the format=flowed specification.
>> It also supports nested quote blocks, which means_
>> this paragraph won't flow into the previous.

The RFC covers edge cases that require special “space-stuffing” rules, but, when editing a text email in an editor, you only need to think about soft and hard line breaks. In my case, Mutt takes care of the rest of the details.

Unfortunately Emacs’s lacks decent support for f=f, though I’m sure a minor mode could be written to make it work well. On the other hand, Vim has been playing an increasing role in my day-to-day editing, and it has excellent built-in support for f=f. Since I’m now using Vim to compose all of my email, I get it for free.

First, I tell Mutt that I want to use f=f in my .muttrc:

set text_flowed

Then in Vim, I add the w flag to formatoptions, which tells it to wrap paragraphs using soft line breaks.

set fo+=w

If I want to inspect my f=f formatting, I temporarily enable the list option, which displays a $ for all newlines.

set list

Although few people would notice a difference, I feel a little bad for not using f=f all these years! A few people may have endured some ugly, non-flowing emails from me. My only condolance is that at least it wasn’t HTML.

It’s not all roses, though. When I reply to a message, Mutt doesn’t insert the quoted text as f=f into my reply, so I have to massage it into f=f myself. Also, just as GitHub doesn’t support Markdown in email responses, neither does it support f=f. When I reply to issues by email, GitHub won’t nicely reflow my carefully crafted f=f message, needlessly making email responses an inferior option.

Features unneeded

One reason I didn’t choose this particular email arrangement 4 years ago was that PGP support was one of my prime requirements. Mutt has solid PGP support, but, with a Maildir setup (i.e. not IMAP), I’d have to use the key on the server, which was out of the question. Since I no longer care about PGP, my email requirements are more relaxed.

Over the years wasn’t making much use of Notmuch’s tagging system. I only used two tags: “unread” and “inbox” (e.g. read, but still needs attention). Otherwise I’d use Notmuch’s powerful search to find what I wanted. I still needed to keep track of the tags I was using, so the Notmuch index, nearly as large as the email messages themselves, became part of my mail backup.

The Maildir format itself supports some flags: passed (P), replied (R), seen (S), trashed (T), draft (D), and flagged (F). These are stored in the message’s filename. In my new configuration, the “seen” tag (inversely) takes the place of Notmuch’s “unread” tag. The “flagged” tag takes place of the “inbox” tag. Normally in Mutt you’d use mailboxes — i.e. Maildir subdirectories — for something like this, but I prefer all my mail to sit in one big bucket. Search, don’t sort.

Since the two flags are part of the filename, I no longer need to include a tag database (i.e. the entire Notmuch index) in the backup, and my mail backups are much smaller. I could continue to use Notmuch for searching, but I’ve settled on mu instead. When I perform a search, mu writes the results to a temporary Maildir using symbolic links, which I visit with Mutt. The mu index is transient and doesn’t need to be backed up.

Mu also manages my contacts alias list. It can produce a Mutt-style alias file based on the contents of my Maildir:

mu cfind --format=mutt-alias > aliases

It’s been really nice to have all my email sitting around as nothing more than a big pile of files like this. I’ve begun writing little scripts to harvest data from it, too.

Configuration files

As with all my personal configuration files, you can see my .muttrc online. The first few weeks I was tweaking this file hourly, but I’ve now got it basically the way I want.

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Chris Wellons