HTML element · data last changed 10 Nov 2026
<rp> in email clients
Works in 15 of 21. Not supported in Gmail, Gmail iOS, Outlook Classic and 1 more. Partial in Gmail Android. Untested in Superhuman.
Your reader in Outlook Classic sees the email without <rp>, even if it looks right where you tested it.
caniemail (MIT) via @emailens/engine 0.18.22
What to do instead in Outlook Classic
If precise ruby rendering matters, build the ruby + parenthesis layout yourself with inline-block spans and explicit positioning. Avoid relying on browser-default ruby semantics in email.
There is no drop-in fix for <rp> in Outlook Classic. Design so the email still reads without it.
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<rp> is not among the 24 features we have screenshotted on real installs. The ones we have →
All 21 clients, problems first
| Client | Support |
|---|---|
| Gmail | Not supported |
| Gmail iOS | Not supported |
| Outlook Classic | Not supported |
| HEY Mail | Not supported |
| Gmail Android | Partial See caveat 1 |
| Superhuman | Untested |
Works in 15: Outlook 365, Outlook (New), Outlook iOS and 12 more. Show all
| Client | Support |
|---|---|
| Outlook 365 | Works |
| Outlook (New) | 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 |
| Proton Mail | Works |
| AOL Mail | Works |
| Fastmail | Works |
Caveats (1)
- 1. Gmail Android: Partial. Supported with non Google accounts only.
Caveats as recorded by caniemail (MIT), one entry per wording.
How <rp> behaves
The <rp> element provides parenthesis fallback for ruby annotations. It is rarely used outside East Asian typography contexts, and email client support is uneven. Production email targeting Japanese or Chinese audiences typically renders ruby manually using inline-block spans for greater control.
- Most email clients ignore the semantic distinction between <rp> and surrounding ruby content.
- Apple Mail respects <rp> visibility rules; other clients often render the parenthesis content inline as regular text.
- Outlook Classic shows <rp> content unconditionally, defeating its hide-when-ruby-supported purpose.
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