line-height

Client-by-client behaviour for line-height

Fully supports line-height (13): Gmail, Gmail Android, Gmail iOS, Outlook 365, Outlook iOS, Outlook Android, Apple Mail, Apple Mail iOS, Yahoo Mail, Samsung Mail, Thunderbird, HEY Mail, Superhuman.

Partial support (2): Outlook (New), Outlook Classic. Expect rendering quirks unique to each engine — partial support typically means a subset of values, an ignored shorthand, or sanitizer-specific rewrites.

When to use line-height in email

• Setting comfortable body-copy leading (typically 1.4–1.6) for readability on small screens.
• Tightening headline leading to keep multi-line titles visually unified.
• Acting as a vertical-spacer trick by setting a large line-height on an empty table cell.

Rendering behaviour and edge cases

• Outlook on Windows uses a different baseline algorithm and can shift text vertically by a pixel or two compared to web browsers.
• Some Android clients scale line-height with user accessibility text-size settings, breaking precise vertical rhythm.
• Setting line-height as a unitless number (e.g. 1.5) is more reliable than fixed px values, as it scales with the inherited font-size.

Recommended fallback strategy

Always pair font-size with an explicit line-height. Prefer unitless values for inherited typography. For pixel-perfect spacer rows, combine an explicit line-height with a height attribute on the <td> to give Outlook a stable vertical baseline.

Fixes & Workarounds