opacity in Fastmail
Works opacity works in Fastmail.
Works in 19 of 21 · not supported in 2
Which clients
- Works
- Gmail, Gmail Android, Gmail iOS, Outlook 365, Outlook (New), Outlook iOS, Outlook Android, Outlook for Mac, Apple Mail, Apple Mail iOS, Yahoo Mail, Yahoo Mail Android, Yahoo Mail iOS, Samsung Mail, Thunderbird, HEY Mail, Proton Mail, Fastmail, Superhuman
- Not supported
- Outlook Classic, AOL Mail
The fix for the clients that need it
Needed in 2 of 21: Outlook Classic and AOL Mail.
Replace opacity with solid color equivalents
.overlay {
/* Use a semi-transparent color instead of opacity */
background-color: #808080;
/* Or for modern clients: rgba(0, 0, 0, 0.5) */
}Show the original
.overlay {
background-color: #000;
opacity: 0.5;
}A free account opens all 21 clients and keeps your checks for 7 days. Create a free account →
Your next question
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Works in 18 of 21 · not supported in 2 · 1 untested
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Works in 17 of 21 · partial in 1 · not supported in 2 · 1 untested
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Works in 13 of 21 · partial in 2 · not supported in 6
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Works in 13 of 21 · partial in 2 · not supported in 6
- Does filter work in Fastmail?
Works in 7 of 21 · not supported in 14
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Works in 7 of 21 · partial in 1 · not supported in 13
Questions
- How many email clients support opacity?
- It works in 19 of 21, not supported in Outlook Classic and AOL Mail.
- Does opacity work in Apple Mail?
- opacity works in Apple Mail. Closest to Fastmail: Apple Mail, which agrees on 192 of the 235 features both are tested on.
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caniemail (MIT) via @emailens/engine 0.18.22 · tested upstream 28 Feb 2019 · data last changed 10 Nov 2026 · Outlook (New) cells are the engine's mapping