HTML element · data last changed 10 Nov 2026
<dfn> in email clients
Works in 17 of 21. Partial in Outlook Classic. Untested in HEY Mail, Fastmail and Superhuman.
Your reader in Outlook Classic may not see <dfn> the way you wrote it, even if it looks right where you tested it.
caniemail (MIT) via @emailens/engine 0.18.22
What to do instead in Outlook Classic
- Partial. The
titleattribute is removed.
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<dfn> is not among the 24 features we have screenshotted on real installs. The ones we have →
All 21 clients, problems first
| Client | Support |
|---|---|
| Outlook Classic | Partial See caveat 1 |
| HEY Mail | Untested |
| Fastmail | Untested |
| Superhuman | Untested |
Works in 17: Gmail, Gmail Android, Gmail iOS and 14 more. Show all
| Client | Support |
|---|---|
| Gmail | Works |
| Gmail Android | Works |
| Gmail iOS | Works |
| 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 |
Caveats (1)
- 1. Outlook Classic: Partial. The
titleattribute is removed.
Caveats as recorded by caniemail (MIT), one entry per wording.
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