Selector or pseudo-class · data last changed 10 Nov 2026
:grouping in email clients
Works in 17 of 21. Not supported in Proton Mail. Partial in Gmail Android and Gmail iOS. Untested in Superhuman.
Your reader in Proton Mail sees the email without :grouping, even if it looks right where you tested it.
caniemail (MIT) via @emailens/engine 0.18.22
What to do instead in Proton Mail
Use selector grouping freely in <style> blocks for cleanliness. For Outlook coverage, duplicate the grouped styles inline on each affected element.
There is no drop-in fix for :grouping in Proton Mail. Design so the email still reads without it.
No signup · Five clients free, Outlook Classic included · All 21 with an account
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:grouping is not among the 24 features we have screenshotted on real installs. The ones we have →
All 21 clients, problems first
| Client | Support |
|---|---|
| Proton Mail | Not supported |
| Gmail Android | Partial See caveat 1 |
| Gmail iOS | Partial See caveat 1 |
| Superhuman | Untested |
Works in 17: Gmail, Outlook 365, Outlook (New) and 14 more. Show all
| Client | Support |
|---|---|
| Gmail | Works |
| Outlook 365 | Works |
| Outlook (New) | Works |
| Outlook Classic | Works |
| Outlook iOS | Works |
| Outlook Android | Works |
| Outlook for Mac | Works |
| Apple Mail | Works |
| Apple Mail iOS | Works |
| Yahoo Mail | Works |
| Yahoo Mail Android | Works |
| Yahoo Mail iOS | Works |
| Samsung Mail | Works |
| Thunderbird | Works |
| HEY Mail | Works |
| AOL Mail | Works |
| Fastmail | Works |
Caveats (1)
- 1. Gmail Android, Gmail iOS: Partial. Not supported with non Google accounts.
Caveats as recorded by caniemail (MIT), one entry per wording.
How :grouping behaves
Selector grouping (a, b, c) applies the same styles to multiple selectors at once. It is a CSS authoring convenience rather than a behavior, when <style> blocks are preserved, grouped selectors behave identically to writing them separately. Outlook strips <style>, so grouped selectors are inert there.
- 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.
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