Email Client Rendering: Why Your Emails May Look Different

When designing emails, it's important to understand that what you see in the editor may not always match exactly what your recipients see. Email clients render HTML differently, and being aware of these differences will help you create more consistent, professional emails.

Understanding Email Rendering Engines

Unlike web browsers, which have become more standardized in recent years, email clients use a variety of rendering engines, some of which are surprisingly outdated.

Microsoft Outlook: The Word Rendering Engine

One of the biggest challenges in email design comes from older versions of Microsoft Outlook. Rather than using a modern browser engine, Outlook 2007 - 2019 use Microsoft Word as their rendering engine. This means:

Limited CSS support compared to modern web standards
No support for most modern CSS properties like display: flex or display: grid
Background images require special workarounds
Spacing and margins can behave unpredictably
Animated GIFs only show the first frame

Other Email Client Variations

Different email clients have their own quirks:

Gmail (Web) – Generally good support, but strips certain CSS properties and the <head> section in some cases
Apple Mail – Excellent rendering, closest to web standards
Yahoo Mail – May alter some formatting and has limited CSS support
Mobile Clients – Often have different default fonts and may resize text for readability

How We Handle Email Rendering

To ensure your emails render as consistently as possible across all email clients, our system automatically applies several best practices:

Table-Based Layouts

Our elements (sections, rows and columns) use HTML tables with inline styles rather than modern CSS layouts like flexbox or grid. While this may seem old-fashioned, it's the most reliable way to ensure consistent rendering in Outlook and other email clients with limited CSS support.

For mobile devices, our elements use media queries to adjust and wrap the columns at appropriate widths.

Automatic CSS Inlining

CSS inlining is applied automatically to your emails. This means styles are written directly onto each HTML element using the style attribute, rather than relying on external stylesheets or <style> blocks that some email clients may strip.

Common Issues and How to Fix Them

Animated GIFs

Animated GIFs won't play in Outlook - only the first frame is displayed. Make sure the first frame still conveys your message effectively, so Outlook users aren't missing out on important content. You can still use animated GIFs which will play the full animation in some mail clients.

Font Differences Causing Alignment Issues

Email clients may not have the same fonts installed as your design system, and fallback fonts can have different character widths and line heights. This can cause content to wrap differently or misalign with adjacent columns.

Tip: Adjust Your Wording

If you have two columns side by side and you want content to align horizontally, try adjusting your wording. Sometimes shortening or lengthening a sentence by a word or two can help text break at the same point, creating visual alignment across columns.

Extra or Missing Spacing

Sometimes email clients will collapse empty space or add unexpected gaps. This can be frustrating when you're trying to create consistent spacing between elements.

Tip: Force Blank Space with a Non-Breaking Space

If you need extra space to appear but it's being collapsed by the email client, try adding a line break followed by a space character (or a non-breaking space  ). This forces email clients to render the blank space rather than collapsing it.

Example: Add <br>  where you need guaranteed vertical spacing.

Background Colors Not Appearing

Outlook in particular has issues with background colors on certain elements. Using table cells (<td>) with background colors is more reliable than using <div> elements.

Best Practices Summary

Test your emails in multiple email clients before sending
Use our built-in elements (sections, row/columns, buttons) and tables for layout
Keep designs simple - complex layouts are more likely to break
Always include fallback fonts in your font stack
Set explicit dimensions on all images
Don't rely on padding alone for spacing - use table cells with fixed widths
Avoid CSS properties that are known to have poor email support
When alignment matters, be prepared to adjust wording rather than fighting the rendering engine

If you're experiencing issues with your email rendering, remember that some variation between email clients is normal. Focus on the most common email clients used by your audience, and prioritize readability over pixel-perfect consistency.