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Does CSS rgba() Work in HTML Email?
RGB functional notation with alpha-channel transparency value (`rgba()`)
Quick Answer
Does rgba() work in HTML email?
The CSS rgba() property is supported in Outlook (Mac / Web), Apple Mail, Samsung Email, Thunderbird, and others. It is NOT supported in Outlook (Windows). Always include a safe fallback for unsupported clients.
Which Email Clients Support CSS rgba()?
CSS support for rgba() across email clients
| Email Client | Desktop | Mobile / Web | Notes |
|---|---|---|---|
| Gmail | ~ Partial | ~ Partial | — |
| Outlook (Windows) | ✗ No | ? | — |
| Outlook (Mac / Web) | ✓ Yes | ✓ Yes | — |
| Apple Mail | ✓ Yes | ✓ Yes | — |
| Yahoo! Mail | ~ Partial | ~ Partial | — |
| Samsung Email | ? | ✓ Yes | — |
| Thunderbird | ✓ Yes | ? | — |
| ProtonMail | ✓ Yes | ✓ Yes | — |
| Fastmail | ✓ Yes | ? | — |
Notes
- #1 Whitespace syntax is not supported (`rgb(0 128 0 / 1)`).
- #2 whitespace syntax (`rgba(0 128 0 / 1)`): when used in the `style` attribute of an element, the whole attribute is stripped. When used inside `<style>`, the whole `<style>` block is stripped.
Frequently Asked Questions
Related CSS Properties
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