:grouping

Client-by-client behaviour for :grouping

Fully supports :grouping (17): Gmail, Outlook 365, Outlook (New), Outlook Classic, Outlook iOS, Outlook Android, Outlook for Mac, Apple Mail, Apple Mail iOS, Yahoo Mail, Yahoo Mail Android, Yahoo Mail iOS, Samsung Mail, Thunderbird, HEY Mail, AOL Mail, Fastmail.

Partial support (2): Gmail Android, Gmail iOS. Expect rendering quirks unique to each engine. Partial support typically means a subset of values, an ignored shorthand, or sanitizer-specific rewrites.

No support (1): Proton Mail. Plan fallbacks for these clients before relying on :grouping in production sends.

Behaviour unverified in: Superhuman.

When to use :grouping in email

• Applying a single base font-family rule to all text-bearing elements at once.
• Resetting margin on multiple heading levels with one rule.
• Sharing dark-mode color overrides across several distinct elements.

Rendering behaviour and edge cases

• Grouping is purely syntactic , supported wherever each individual selector is supported.
• Outlook ignores all <style>-based grouping.
• Long groups can become hard to maintain , keep groups focused on a single styling concern.

Recommended fallback strategy

Use selector grouping freely in <style> blocks for cleanliness. For Outlook coverage, duplicate the grouped styles inline on each affected element.

Fixes & Workarounds