Why HTML Email Is Still a Completely Different Beast to Web Development

At first glance, HTML email development and web development look like close relatives. Both use HTML and CSS, both start with a design that needs turning into something functional, and both need to work across different screen sizes. It’s easy to assume that a developer who can build a responsive website can approach an email campaign in much the same way.

In reality, the two disciplines have evolved very differently. Browsers have spent years moving towards greater consistency and support for modern standards, while email clients remain a much more fragmented environment. An email that looks exactly as intended in Apple Mail can behave differently in Gmail or Outlook, while desktop and mobile versions introduce their own quirks. Add dark mode, image blocking and inconsistent CSS support, and even a relatively simple-looking campaign can require a surprising amount of work behind the scenes.

That’s why HTML email development has become a discipline in its own right. The end result might look simple in the inbox, but getting it to look simple everywhere is the difficult part.

Why HTML Email Development Is Different

Modern web developers have access to an incredibly capable toolkit. Flexbox and CSS Grid make complex layouts easier to control, JavaScript enables sophisticated interactions, and responsive frameworks make adapting interfaces across devices considerably easier.

Email developers don’t have the same freedom. Every email is displayed inside somebody else’s application, and each client decides which parts of HTML and CSS it supports and how they should be interpreted. Developers can check current support for individual HTML and CSS features using resources such as Can I email before deciding whether a technique is reliable enough for production.

As a result, techniques that might feel outdated in normal web development remain commonplace in email. Tables are still widely used to create dependable layouts, important CSS is often inlined, and developers frequently need fallback approaches for clients that don’t support the preferred implementation.

The priority isn’t writing the most elegant code. It’s producing dependable code that survives the journey from the marketing platform to the recipient’s inbox.

Outlook Rendering and Bulletproof Email Code

Anyone who regularly builds marketing emails will eventually have a story about Outlook. Different versions have historically created some of the biggest rendering challenges in email development, particularly around spacing, backgrounds, buttons and more complicated layouts.

This is where email-specific techniques become important. Developers may use Microsoft conditional comments to serve Outlook-specific markup, while so-called bulletproof buttons can use VML alongside standard HTML and CSS to maintain CTA styling in versions of Outlook where normal CSS approaches aren’t reliable.

A production-ready email therefore shouldn’t simply be coded until it looks right in a browser preview. Specialist HTML email development anticipates these awkward environments from the beginning and builds suitable fallbacks into the email.

That doesn’t mean every client has to reproduce every pixel identically. What matters is protecting the brand, hierarchy, readability and functionality of the campaign so the recipient gets a consistent experience even when the underlying rendering technology is different.

Responsive Email Design

Responsive email presents another set of challenges. A desktop design might contain multiple columns, large imagery and carefully balanced spacing, but simply stacking everything vertically on a phone can produce an extremely long and confusing email.

Developers need to consider how tables collapse or stack at smaller widths, whether typography remains readable, whether buttons provide comfortable touch targets and how images resize without breaking their containers. Media queries can provide additional control in clients that support them, while sensible fluid layouts and fallbacks help maintain usability elsewhere.

Content hierarchy matters just as much as the code. The primary message and call to action still need to be obvious after the layout changes. The best responsive emails aren’t merely capable of becoming narrower; they’re designed around how somebody is actually likely to consume the message on a smaller screen.

Dark Mode Email Development

Dark mode added another variable to an already inconsistent environment. Some email clients respect CSS such as prefers-color-scheme, allowing developers to define alternative colours for users who have selected dark mode. Others apply their own colour transformations, sometimes changing backgrounds and text regardless of what the original design intended.

This can cause practical problems. A dark logo can disappear against a newly darkened background, brand colours can change and transparent imagery may suddenly reveal edges that weren’t visible against the original design.

There isn’t one universal fix, so dark mode needs to be considered as part of both design and development. Where supported, developers can use targeted CSS to control the experience. Elsewhere, careful choices around imagery, contrast, transparent assets and fallback colours can make the email more resilient when the client takes control.

Turning Figma Designs Into HTML Email

A polished Figma file can look finished, but turning it into a reliable email involves considerably more than translating visual elements into HTML. Fonts may require suitable fallbacks, complicated layouts may need restructuring, imagery needs optimisation and responsive behaviour has to be decided rather than assumed.

The developer also needs to understand what happens after the first campaign. Is the email a one-off build, or does the marketing team need to edit it? Which sections should be reusable? What happens if a headline becomes twice as long, a product is removed or somebody adds an extra content block?

A specialist email design and development studio such as Email Squad has to bridge that gap between the freedom of the design canvas and the restrictions of the inbox. Sometimes that means making a small adjustment rather than reproducing the Figma file literally, because a visually perfect implementation isn’t particularly useful if it falls apart when a subscriber opens it.

Building Reusable Email Templates

The challenge becomes even more interesting when an email needs to work repeatedly rather than for a single campaign. A developer isn’t only considering today’s content; they’re creating something that needs to survive whatever the marketing team puts into it next month.

This is why modern email templates increasingly behave like small design systems. Rather than creating one rigid layout, a template can contain tested modules for headers, hero areas, text and image combinations, product cards, calls to action, footers and other common content.

Those modules can then be assembled in different combinations while maintaining the same underlying brand rules and tested code. Editable areas remain genuinely useful to marketers without giving users so much freedom that every campaign gradually drifts away from the original design.

It also makes the development work more valuable over time. Instead of repeatedly solving the same rendering problems, the difficult coding and testing happens at component level and the resulting modules can be reused across dozens of campaigns.

Testing HTML Emails Across Clients

Testing is also part of email development rather than something added at the end. Links, images, responsive behaviour and content all need checking, but the email also needs to be viewed across the clients and devices that matter to its audience.

This becomes especially important with reusable components. Fixing an Outlook problem or mobile layout issue in a module before launch can prevent that same issue appearing in every future campaign built with it.

Browser previews are useful during development, but they don’t tell the whole story. The real test is what happens when the code reaches Gmail, Outlook, Apple Mail and the other environments in which subscribers actually open it.

Simple in the Inbox, Complicated Underneath

A well-developed marketing email shouldn’t feel technically impressive to the person receiving it. The branding should look right, the message should be easy to understand, the hierarchy should be obvious and the call to action should work. Whether it was opened on a phone, in Gmail or through Outlook shouldn’t become the recipient’s problem.

That’s the strange thing about email development: the better the work behind the scenes, the less anybody notices it.

Web development and email development might share HTML and CSS, but they’re solving different problems. One increasingly operates inside capable, standardised browsers. The other still has to deliver a consistent experience across an ecosystem of inboxes with different capabilities and rendering behaviours.

The finished email may look simple. Achieving that simplicity is where the specialist work comes in.

Author

Barry Button is part of the team at Email Squad, a specialist email design and development studio helping brands and agencies create better campaigns, templates, flows and email design systems. He knows his way around an inbox and has a particular dislike of broken layouts, rogue spacing and anything Outlook decides to do differently.