CSS property · data last changed 10 Nov 2026
outline in email clients
Works in 20 of 21. Not supported in Outlook Classic.
Your reader in Outlook Classic sees the email without outline, even if it looks right where you tested it.
caniemail (MIT) via @emailens/engine 0.18.22
What to do instead in Outlook Classic
There is no drop-in fix for outline in Outlook Classic. 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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outline 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 | Not supported |
Works in 20: Gmail, Gmail Android, Gmail iOS and 17 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 |
| HEY Mail | Works |
| Proton Mail | Works |
| AOL Mail | Works |
| Fastmail | Works |
| Superhuman | Works |
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fix
Every feature in Outlook Classic · All email CSS features · What real installs show
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