How macOS Mojave's Dark Mode for Apple Mail Impacts Email Design


On June 4th at WWDC 2018 Apple announced that macOS Mojave would be the upcoming release for Mac computers with general availability this fall. One of the prominent new features macOS Mojave introduces is Dark Mode.

macOS Mojave's Dark Mode

You can watch the full demo video of Dark Mode from WWDC 2018 here.

Dark Mode is available if you are a part of the Apple Beta Software Program and install the macOS Mojave beta. To enable it, users can go to System Preferences > General and select the Appearance.

Dark Mode provides a dark theme for all major desktop apps, including Finder, iTunes, Photos, and what's most important for us email geeks: Apple Mail.

macOS Mojave automatically detects the time of day and switches between Light/Dark modes by default. macOS Mojave also features a dynamic wallpaper background by default that gradually changes throughout the day as well (a neat little feature).

Apple Mail in Light Mode
Apple Mail in Light Mode
Apple Mail in Dark Mode
Apple Mail in Dark Mode

Is Apple the first to introduce a Dark Mode?

Nope, in fact Microsoft actually beat them to it with Windows 10.

Windows 10 Dark Mode

It's just a big deal now because...well, Apple.

How do you like using Dark Mode?

I friggin love it. I pretty much use this mode exclusively. You're either a Light or Dark apps theme kinda person, and I'm so #TeamDarkTheme. Let me know: which team are you on?

Which kind of person are you for using apps/sites? (I’m so #TeamDarkTheme for all the things)

— Kevin Mandeville (@KevinMandeville) September 11, 2018

How does this impact email design?

👍 Good news: Dark Mode does not impact HTML emails with images at all by default (even if the only image is a tracking pixel). Dark Mode is only applied to personal, rich text (no images), plain text emails. Even if you do not have a background color defined by default in your HTML email with images, the background is still rendered as white. So you don’t have to worry about Dark Mode messing with your code or rendering experience for regular HTML emails with images out of the box.

Personal Email in Dark Mode
Personal Email in Dark Mode
Plain Text Email in Dark Mode
Plain Text Email in Dark Mode
HTML Email in Dark Mode
HTML Email in Dark Mode
(No background set)

However, this creates a very jarring experience for end users in Dark Mode IMO. Having emails that switch from being dark to light (and vice versa) makes your eyes bleed. 😭

What's odd is that Safari has separate behavior than Apple Mail. By default, if you do not have a background color applied for your website, Dark Mode in Safari will apply its default dark background, causing the rest of the website design to "break." So web designers actually have it worse than email designers for once. 😂

I suspected the same, but this doesn’t seem to be the case.. 🤔

— Kuldar @ 🇩🇪 (@kkuldar) June 11, 2018

How can we optimize our email designs for Dark Mode?

👎 Bad news: Unfortunately, there is no way to specifically target Dark Mode via CSS. Dark Mode is introducing a new user setting that isn't supported by any universal standard yet.

This has triggered a massive discussion around the necessity for media query support for dark themes. Apple is currently experimenting with a private API for Dark Mode using this media query:

@media (prefers-dark-interface)

*Hat tip to Keith Cirkel for the find

This media query can be used for rich text emails without images currently, but it is not applicable for HTML emails with images. However, Apple is being cautious about exposing anything as they want to work to create a universal standard:

You said it, not me. ;)

We’re considering adding a web-exposed media query, but it requires some more thought. Standardization is a thing, and API is forever. :)

We’d love to hear any thoughts y’all have in Radar or the public WebKit bug tracker (

— Ricky Mondello (@rmondello) June 14, 2018

Microsoft has already introduced this vendor-specific media query that describes whether an application is being displayed in high contrast mode:

@media (-ms-high-contrast)

There is also this fantastic thread in the W3C CSS Working Group's Github on this issue. Personally, I do fancy the proposition of prefers-ui-theme with the values light-on-dark, dark-on-light, and no-preference. It's logical, specific, and simple.

👍 Good news: We can optimize our email designs by creating a Dark Mode or accessibility switcher with WebKit targeting that lets users toggle whether they want a light or dark design.

Here is a basic demo concept:

You can send yourself a test of the above code in Dark Mode to play with. The simple premise is you use a checkbox that changes the background and text color styles depending on whether it is toggled or not. This type of interactivity is supported in primarily Apple Mail, iOS Mail, and Outlook for Mac, which accounts for ~42% of global market share currently.

Take a look at a full email designed to have a light and dark mode with an accessibility switcher.

Paul Airy's Accessbility Switcher
Paul Airy's Accessbility Switcher

This technique was created Paul Airy in his Beyond the Envelope Type:E newsletter.

Here are macOS Mojave's Dark Mode Colors:

Background: #2d2d2d
Text Color: #dfdfdf
Link Color: #1b89ef

So, given those values, we can create an interactive switcher that changes our design to use a background of #2d2d2d to match the rest of Apple Mail's Dark Mode design and use the standard text colors Dark Mode uses or customize to other colors as we see fit.

This also provides the opportunity to capture subscribers' preference over whether they prefer a light or dark theme email for consumption in order to display by default. Imagine a subscriber setting their theme preference in your app or newsletter settings, which gets stored in your ESP, and then gets served as the default theme for all future emails. I'm personally excited and hopeful that we will see this level of personalization stem from this environment. Granted, this approach isn't entirely bulletproof (nothing is with email), as users could open in another app for instance, but at least takes their preference into account (this also highlights why we need support for targeting dark modes).

If you believe in creating the best experience possible for your subscribers, supporting Dark Mode isn't a nice-to-have, it's a necessity.

If you believe in creating the best experience possible for your subscribers, supporting Dark Mode isn't a nice-to-have, it's a necessity. Developing a light/dark theme switcher really isn't that much overhead or investment and is a scalable implementation if done properly. Providing a high contrast version for our emails is something we should be doing regardless of Dark Mode anyways. Many won't take the time to optimize for it, but it's going to separate the bad/mediocre/good from the great. World class brands and email marketing teams will support Dark Mode.

The impact of Dark Mode on email design

Dark Mode creates yet another environment for to account our email designs for. It highlights the ever-growing need of needing to become context-aware for subscribers.

Email design challenges aren't always about rendering. Underneath it all, the main challenge is always about crafting personal experiences for subscribers. Dark Mode is just the latest iteration of this.

I love this environment being added into the world of email design because it doesn't introduce a rendering challenge per se, but a design strategy and accessibility one. Email design challenges aren't always about rendering. Underneath it all, the main challenge is always about crafting personal experiences for subscribers. Dark Mode is just the latest iteration of this.

I do ultimately believe that standards will introduce a media query that allows us to target dark themes universally, which will be a major win for developers everywhere. This is sorely needed. Until then, we can enhance with a WebKit-targeted theme switcher for now to provide the best possible experience for subscribers.

What are your thoughts?

How will you design for Dark Mode? Do you have any unique ideas on how to approach it? Will you be implementing a light/dark theme switcher? Let me know @KevinMandeville.

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