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Muon, the Mutt theme for ProtonMail—it doesn't get smaller than this.
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Introducing Muon

Muon, the Mutt theme for Proton—it doesn't get smaller than this.

What is it?

This custom CSS strips out all of the mouse-driven UI from Proton Mail, making it similar to the command-line email client Mutt. This means that you navigate it (almost) entirely though keyboard shortcuts. (Press ? to see a list of ProtonMail's keyboard commands.)



"Installation" instructions

Copy the CSS from muon.css into the Custom Theme box at


Wait, really?


Should I actually use this?

Probably not. You have to be a special kind of crazy to want to turn a perfectly good webmail client into an imitation of a CLI app. If nothing else, you should probably just set up the real mutt and use ProtonMail's IMAP bridge to use the real thing if that's your jam.

Ok, but do you actually use it?

Yep, every day—I'm that special kind of crazy!

If I do use it, how does it work?

Mostly, you just use the ProtonMail's keyboard commands. As I mentioned up top, press ? to see a list of the keyboard commands. Ironically enough, the list of keyboard commands itself doesn't support keyboard navigation that well, but you can <TAB> though the various options. That lets you navigate to your inbox or other built-in ProtonMail folders (Spam, Sent, etc.).

Two other commands to remember: <SHIFT-space> opens the command pallet, which lets you do a few more things with your keyboard. And / jumps you to the search bar, which will prove useful for more than just searching for emails.

Should I know anything else about keyboard navigation other than pressing ??

Well, you can jump to a specific folder by searching for in:$FOLDER_NAME. For example, I jump to my promo folder by pressing / and then searching in:promo. No, you can't do in:p*. And no, in:p<TAB> doesn't autocomplete. Yes, I agree it should. I opened an issue. Until that's resolved, I recommend short folder names.

How do I use this to send Rich Text emails instead of plaintext?

You don't. Even asking that question makes me wonder if you really even get the whole idea behind this theme.

Wait, I just noticed something—you turned off the button for settings! How do I get to settings? I can't even turn this blasted thing off!

Of course I turned it off—it was a button, after all! And what good would something with vim-inspired keybindings be if it weren't at least a little hard to quit?

Fortunately, ProtonMail follows a sane URL scheme for their app, so you can get to any of the settings pages by going to that page directly. Here's a list of all the URLs you might want:

Specifically, if you want to turn it off, you'll want the URL. (No promises that you can use the settings pages without a mouse, though, sadly enough).

Ok, sounds like I can do a lot. Is there anything I can't do without a mouse?

You can't delete messages from the Trash or empty the Trash (though they're auto-deleted on their own). You also can't add a custom filter based on an existing email message, though I left the button alone for that so you can still get out your mouse like a caveman if you need to.

Any other bugs I should know about?

This isn't exctly a bug with this theme, but you should know that opening a new message results in a new draft being created—even if you close the message without adding any text. This can clutter up your Drafts folder, especially because keyboard navigation makes it easier to open a new message. Again, I've opened an issue.

These questions weren't actually asked frequently, were they?

Nope! But, then again, neither are the questions in most FAQs.

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