Email CSS & HTML Support

Check CSS and HTML compatibility across 21 email clients. Based on real-world testing data from caniemail.com · 255 features, updated regularly.

Data report

The State of Email CSS 2026

Only 6 of 255 features work in every client. See the full leaderboard, the Outlook traps, and the safe list →

Email Clients

Gmail

webmail

Gmail Web

124 supported15 partial

Gmail Android

mobile

Gmail Mobile

82 supported61 partial

Gmail iOS

mobile

Gmail Mobile

85 supported52 partial

Outlook 365

webmail

Outlook Web

138 supported32 partial

Outlook (New)

desktop

Outlook Web

45 supported24 partial

Outlook Classic

desktop

Microsoft Word

45 supported20 partial

Outlook iOS

mobile

Outlook Mobile

152 supported16 partial

Outlook Android

mobile

Outlook Mobile

147 supported14 partial

Outlook for Mac

desktop

WebKit

199 supported14 partial

Apple Mail

desktop

WebKit

238 supported12 partial

Apple Mail iOS

mobile

WebKit

235 supported9 partial

Yahoo Mail

webmail

Yahoo

109 supported27 partial

Yahoo Mail Android

mobile

Yahoo

104 supported27 partial

Yahoo Mail iOS

mobile

Yahoo

102 supported25 partial

Samsung Mail

mobile

Samsung

210 supported21 partial

Thunderbird

desktop

Gecko

203 supported4 partial

HEY Mail

webmail

WebKit

165 supported7 partial

Proton Mail

webmail

Proton

192 supported13 partial

AOL Mail

webmail

AOL

106 supported24 partial

Fastmail

webmail

Fastmail

163 supported4 partial

Superhuman

desktop

Blink

84 supported5 partial

Features by Category

HTML Elements40

CSS At-Rules5

@font-face @import @keyframes @media @supports

Pseudo-Elements6

::after ::before ::first-letter ::first-line ::marker ::placeholder

Pseudo-Classes & Selectors34

CSS Functions8

calc clamp conic-gradient fit-content linear-gradient max min radial-gradient

CSS Properties162

!important accent-color align-items animation aspect-ratio backdrop-filter background background-blend-mode background-clip background-color background-image background-origin background-position background-repeat background-size bimi block-size border border-collapse border-image border-inline border-inline-individual border-inline-longhand border-radius border-radius-logical border-spacing bottom box-shadow box-sizing caption-side clear clip-path color color-scheme column-count columns css-comments cursor custom-properties direction display display:flex display:grid display:none empty-cells filter flex-direction flex-wrap float font font-family font-kerning font-size font-size-adjust font-stretch font-weight gap grid-template-columns height hyphenate-character hyphenate-limit-chars hyphens inert inline-size inset justify-content left letter-spacing light-dark line-height list-style list-style-image list-style-position list-style-type margin margin-block-start-end margin-inline-block margin-inline-start-end mask-image max-block-size max-height max-inline-size max-width min-block-size min-height min-inline-size min-width mix-blend-mode modern-color nesting object-fit object-position opacity orphans outline outline-offset overflow overflow-wrap padding padding-block-start-end padding-inline-block padding-inline-start-end position resize rgb rgba right scroll-snap shape-margin shape-outside system-ui tab-size table-layout text-align text-align-last text-decoration text-decoration-color text-decoration-line text-decoration-skip-ink text-decoration-style text-decoration-thickness text-emphasis text-emphasis-position text-indent text-justify text-orientation text-overflow text-shadow text-transform text-underline-offset text-underline-position text-wrap top transform transition unit-ch unit-cm unit-em unit-ex unit-in unit-initial unit-mm unit-pc unit-percent unit-pt unit-px unit-rem unit-vh unit-vmax unit-vmin unit-vw user-select vertical-align visibility white-space white-space-collapse widows width word-break word-spacing writing-mode z-index

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