Creating responsive HTML emails is notoriously difficult. Unlike modern web browsers, email clients like Outlook, Gmail, and Apple Mail all use entirely different rendering engines.
To help you navigate this minefield, here are the core best practices we use when building templates for CodedMails.
1. Leverage MJML
Don't write raw HTML tables anymore. Use a dedicated email framework like MJML. MJML abstractions compile down to compliant, responsive HTML that safely bypasses client quirks. By writing 80% less code, your risk of breaking layouts drops significantly. At CodedMails, our entire architecture relies on MJML.
2. Inline Your CSS
Most email clients explicitly strip out <style> blocks in the <head> of your document. To ensure your styles render correctly, you must inline your CSS directly onto the HTML elements. (Fortunately, if you use MJML, this happens automatically during the compilation process).
3. Build for Mobile First
Statistics show that the majority of emails are now opened on mobile devices. Ensure your multi-column layouts gracefully collapse into single-column layouts. Use large, legible typography and touch-friendly buttons with ample padding.
4. Keep Images Lightweight, but High Quality
Always use the alt tag for images—many email clients block images by default, and a descriptive alt tag preserves the message. Compress your images, but remember to double their pixel dimensions (and size them down using HTML width attributes) for retinal displays to ensure they appear sharp.
5. Always Test Cross-Client
A template might look fantastic on Apple Mail but completely fall apart on Outlook 2019. Testing across clients is non-negotiable. At CodedMails, we test our templates against 80+ clients to guarantee rock-solid reliability.
By following these fundamental practices, you can save hours of debugging and deliver beautiful experiences straight to your users' inboxes.