Your Logo Looks Perfect in Light Mode. Here's What It Becomes in Dark Mode.

A large and growing share of email opens now happen with dark mode switched on. That shift changes the entire calculus of picking an image format for a newsletter, because the image you're choosing doesn't get shown once, it gets shown in two different environments, and most format advice only accounts for one of them. Here's what actually happens to a handful of common email images once dark mode gets involved, and what survives it.

The three ways your image's background can betray you

Email clients don't agree on what "dark mode" even means to an incoming email, and they fall into three distinct camps. Some clients fully invert everything, flipping light backgrounds to dark and dark text to light across the entire message. Others apply partial inversion, changing backgrounds while trying to leave images and some text alone, a behavior available to clients that support the prefers-color-scheme media query, giving the sender some actual control over the result. A third group does nothing at all, rendering the email exactly as designed regardless of the recipient's system theme. Which behavior a given recipient sees depends on the specific client and, often, the specific version and platform it's running on, Microsoft's own documentation notes that Outlook's mobile apps don't convert images to dark mode the way some other clients do, so it's worth testing your actual send list's major clients rather than assuming a fixed category for each one.

What your transparent logo becomes

A logo exported as a PNG with a transparent background is standard advice, and it's correct advice for light mode. In a fully-inverting client, that same file becomes a specific, well-documented problem: dark logo artwork sitting on what the recipient now sees as a black background produces a shape that either disappears into the surrounding dark chrome or reads as a stray dark blob with no visible edges, since the transparency that made it blend into a white background now makes it blend into a black one instead. Some clients compound this further; Gmail on Android is known to auto-invert white icon artwork specifically, turning white social icons into near-black shapes on a dark background where they become nearly invisible.

What your white-background product photo becomes

A product photo shot on a clean white background, a standard choice for e-commerce, runs into the opposite version of the same problem. In a partially-inverting client, the white square around the product doesn't necessarily invert with the rest of the layout, leaving a bright white rectangle sitting in the middle of an otherwise dark email, an effect senders sometimes describe as the photo suddenly wearing a glowing frame it never had in light mode.

What your animated GIF becomes, in one specific client

This failure has nothing to do with dark mode and everything to do with which rendering engine opens the email. Classic Outlook on Windows doesn't use a browser engine at all, it renders HTML email through Microsoft Word's layout engine, a longstanding quirk that also explains Outlook's historically weak support for CSS backgrounds and grid layouts. One documented consequence, confirmed directly in Microsoft's own support materials: an animated GIF can show only its first frame in this environment, depending on the specific animation and the recipient's settings, rather than playing the way it would in a browser. Classic Outlook is being phased out in favor of a new, browser-engine-based Outlook, but the transition is gradual and enterprise environments in particular are expected to keep running the older engine for a while yet, so this isn't a fading concern in the near term.

The three formats that actually survive email's own limitations

Format support in email lags well behind browsers, and the gap is wider than most senders assume. WebP has landed in Apple Mail and recent Outlook builds but is still missing from older Outlook desktop installations still in active use. AVIF is close to entirely unsupported across major email clients as of 2026, despite being well past mainstream in browsers. That leaves JPEG, PNG, and GIF as the safest, most broadly compatible choices for anything embedded directly in an email, PNG specifically for logos, icons, and anything needing transparency or sharp text, JPEG for photography, GIF where simple looping animation matters and an occasional first-frame-only fallback in some environments is an acceptable trade-off.

Fixing the specific failure, not the whole image

None of the failures above require abandoning the format that causes them, they require designing around the specific mechanism. A logo can survive full inversion with a thin light-colored outline or stroke around the artwork and a small amount of padding, so it reads as a distinct shape rather than dissolving into whatever background color the client decided to apply. Product photography on a stark pure white or pure black background is worth reconsidering specifically because some clients target the exact hex values #000000 and #ffffff for hardcoded inversion, a soft off-white or off-black background sidesteps that trigger entirely. For anything sent to a list where Outlook desktop still makes up a meaningful share of opens, treating an animated GIF's first frame as the real design, not an acceptable fallback, keeps the email looking intentional in that environment rather than broken.

The one thing no format choice can fix

A meaningful share of recipients never see any embedded image at all on first open, Outlook and many corporate mail environments block remote images by default until the recipient explicitly allows them. Every image format decision above only matters once that first hurdle is cleared, which is the entire reason alt text carries more practical weight in email than almost anywhere else the same image might appear. A logo, a product photo, or a hero banner with no meaningful alt text is, to a meaningful fraction of every send, simply a blank space, regardless of which format sits behind it. Optimize and prepare your email assets easily in your browser using our converter.