When pasting custom HTML into Sparrow’s email feature, users may notice that emails display correctly in most modern email clients but appear broken, misaligned, or inconsistent in Microsoft Outlook (desktop version). This issue arises because
Outlook does not use a modern web rendering engine like Chrome or Edge but instead relies on Microsoft Word's rendering engine, which lacks support for many modern HTML and CSS features.
1. Word Isn't a Web Browser
- Outlook uses Microsoft Word to render emails, which is designed for document processing, not web standards.
- Unlike web browsers that follow CSS3 and HTML5, Word lacks support for many modern styles.
2. Limited CSS Support
- No support for flexbox, grid, media queries, or CSS animations.
- Limited support for positioning (no
float,fixed,sticky). - Margins and padding often render inconsistently.
3. Tables Are King
- Since Word struggles with
div-based layouts, tables remain the most reliable way to structure emails. - Many modern email designs still rely on nested tables because of this.
4. No Support for External Fonts
- You can only use web-safe fonts (Arial, Times New Roman, Verdana, etc.).
- Custom web fonts (
@font-face) won’t work.
5. Poor Image Handling
- Images don’t always scale properly.
- No support for SVGs.
6. Varying Support Across Versions
- Outlook 2016, 2019, and 365 all have slight differences in rendering.
- Windows and Mac versions behave differently.
How to Fix It?
- Use tables instead of divs for layout.
- Inline CSS instead of external stylesheets.
- Avoid CSS animations, JavaScript, or complex positioning.
- Test emails in Litmus or Email on Acid to see how Outlook handles them.
Outlook is basically stuck in the early 2000s when it comes to email rendering, and unless Microsoft completely rewrites it with a modern engine, this issue isn’t going away.