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6 of 300 features work in all 21 email clients. 28 more work in every client that has tested them.

Look up any CSS property, HTML element or attribute: where it works, where it is not supported, and the fix when there is one.

@emailens/engine 0.18.22 · data last changed 10 Nov 2026

Where to start

  • padding

    Works in 20 of 21 · partial in 1

    Outlook Classic: Partial Fix for Outlook Classic

  • word-break

    Works in 4 of 21 · partial in 12 · not supported in 5

    Outlook Classic: Not supported Fix for Outlook Classic

Every feature, by category

HTML Elements 48
  • <abbr>

    Works in 14 of 21 · not supported in 6 · 1 untested

    Outlook Classic: Not supported

  • <acronym>

    Works in 13 of 21 · not supported in 5 · 3 untested

    Outlook Classic: Not supported

  • <address>

    Works in 20 of 21 · 1 untested

    Outlook Classic: Works

  • <audio>

    Works in 4 of 21 · not supported in 17

    Outlook Classic: Not supported

  • <base>

    Works in 4 of 21 · partial in 13 · not supported in 3 · 1 untested

    Outlook Classic: Not supported

  • <bdi>

    Works in 6 of 21 · not supported in 14 · 1 untested

    Outlook Classic: Not supported

  • <blockquote>

    Works in 19 of 21 · partial in 1 · 1 untested

    Outlook Classic: Works

  • <body>

    Works in 5 of 21 · partial in 9 · not supported in 6 · 1 untested

    Outlook Classic: Works

  • <button type="reset">

    Works in 10 of 21 · partial in 2 · not supported in 8 · 1 untested

    Outlook Classic: Not supported

  • <button type="submit">

    Works in 11 of 21 · partial in 1 · not supported in 8 · 1 untested

    Outlook Classic: Not supported

  • <code>

    Works in 20 of 21 · 1 untested

    Outlook Classic: Works

  • <del>

    Works in 20 of 21 · 1 untested

    Outlook Classic: Works

  • <dfn>

    Works in 17 of 21 · partial in 1 · 3 untested

    Outlook Classic: Partial

  • <dialog>

    Works in 5 of 21 · not supported in 15 · 1 untested

    Outlook Classic: Not supported

  • <div>

    Works in 20 of 21 · 1 untested

    Outlook Classic: Works

  • <form>

    Works in 10 of 21 · partial in 4 · not supported in 7

    Outlook Classic: Not supported Fix for Outlook Classic

  • <h1>

    Works in 20 of 21 · 1 untested

    Outlook Classic: Works

  • <hr>

    Works in 18 of 21 · 3 untested

    Outlook Classic: Works

  • <img>

    Works in 19 of 21 · 2 untested

    Outlook Classic: Works

  • <input type="checkbox">

    Works in 16 of 21 · partial in 1 · not supported in 3 · 1 untested

    Outlook Classic: Not supported

  • <input type="hidden">

    Works in 16 of 21 · partial in 1 · not supported in 3 · 1 untested

    Outlook Classic: Not supported

  • <input type="radio">

    Works in 16 of 21 · partial in 1 · not supported in 3 · 1 untested

    Outlook Classic: Not supported

  • <input type="reset">

    Works in 15 of 21 · partial in 2 · not supported in 3 · 1 untested

    Outlook Classic: Not supported

  • <input type="submit">

    Works in 12 of 21 · partial in 1 · not supported in 7 · 1 untested

    Outlook Classic: Not supported

  • <input type="text">

    Works in 13 of 21 · partial in 1 · not supported in 6 · 1 untested

    Outlook Classic: Not supported

  • <link>

    Works in 3 of 21 · not supported in 18

    Outlook Classic: Works

  • <marquee>

    Works in 8 of 21 · partial in 6 · not supported in 6 · 1 untested

    Outlook Classic: Not supported

  • <meter>

    Works in 11 of 21 · partial in 1 · not supported in 8 · 1 untested

    Outlook Classic: Not supported

  • <object>

    Works in 1 of 21 · partial in 3 · not supported in 16 · 1 untested

    Outlook Classic: Not supported

  • <p>

    Works in 20 of 21 · 1 untested

    Outlook Classic: Works

  • <picture>

    Works in 4 of 21 · partial in 1 · not supported in 16

    Outlook Classic: Not supported

  • <pre>

    Works in 20 of 21 · 1 untested

    Outlook Classic: Works

  • <progress>

    Works in 6 of 21 · partial in 1 · not supported in 13 · 1 untested

    Outlook Classic: Not supported

  • <rp>

    Works in 15 of 21 · partial in 1 · not supported in 4 · 1 untested

    Outlook Classic: Not supported

  • <rt>

    Works in 15 of 21 · partial in 1 · not supported in 4 · 1 untested

    Outlook Classic: Not supported

  • <ruby>

    Works in 15 of 21 · partial in 1 · not supported in 4 · 1 untested

    Outlook Classic: Not supported

  • <select>

    Works in 14 of 21 · partial in 3 · not supported in 3 · 1 untested

    Outlook Classic: Not supported

  • <small>

    Works in 20 of 21 · 1 untested

    Outlook Classic: Works

  • <span>

    Works in 20 of 21 · 1 untested

    Outlook Classic: Works

  • <strike>

    Works in 17 of 21 · partial in 2 · not supported in 1 · 1 untested

    Outlook Classic: Works

  • <strong>

    Works in 20 of 21 · 1 untested

    Outlook Classic: Works

  • <style>

    Works in 16 of 21 · partial in 5

    Outlook Classic: Partial

  • <svg>

    Works in 5 of 21 · partial in 1 · not supported in 15

    Outlook Classic: Not supported Fix for Outlook Classic

  • <table>

    Works in 20 of 21 · 1 untested

    Outlook Classic: Works

  • <textarea>

    Works in 13 of 21 · partial in 2 · not supported in 5 · 1 untested

    Outlook Classic: Not supported

  • <ul>

    Works in 7 of 21 · partial in 13 · 1 untested

    Outlook Classic: Partial

  • <video>

    Works in 3 of 21 · partial in 2 · not supported in 16

    Outlook Classic: Not supported Fix for Outlook Classic

  • <wbr>

    Works in 16 of 21 · partial in 1 · not supported in 3 · 1 untested

    Outlook Classic: Not supported

HTML Attributes 22
  • [align]

    Works in 17 of 21 · partial in 3 · 1 untested

    Outlook Classic: Works

  • [aria-describedby]

    Works in 9 of 21 · not supported in 11 · 1 untested

    Outlook Classic: Not supported

  • [aria-hidden]

    Works in 13 of 21 · not supported in 7 · 1 untested

    Outlook Classic: Not supported

  • [aria-label]

    Works in 13 of 21 · not supported in 7 · 1 untested

    Outlook Classic: Not supported

  • [aria-labelledby]

    Works in 7 of 21 · not supported in 13 · 1 untested

    Outlook Classic: Not supported

  • [aria-live]

    Works in 8 of 21 · not supported in 12 · 1 untested

    Outlook Classic: Not supported

  • [background]

    Works in 16 of 21 · partial in 2 · not supported in 2 · 1 untested

    Outlook Classic: Not supported

  • [cellpadding]

    Works in 18 of 21 · 3 untested

    Outlook Classic: Works

  • [cellspacing]

    Works in 18 of 21 · 3 untested

    Outlook Classic: Works

  • [command]

    Works in 3 of 21 · partial in 1 · not supported in 13 · 4 untested

    Outlook Classic: Not supported

  • [dir]

    Works in 19 of 21 · partial in 1 · 1 untested

    Outlook Classic: Partial

  • [height]

    Works in 18 of 21 · partial in 1 · not supported in 1 · 1 untested

    Outlook Classic: Partial

  • [hidden]

    Works in 5 of 21 · not supported in 13 · 3 untested

    Outlook Classic: Not supported

  • [lang]

    Works in 15 of 21 · partial in 4 · not supported in 1 · 1 untested

    Outlook Classic: Works

  • [loading]

    Works in 4 of 21 · partial in 1 · not supported in 15 · 1 untested

    Outlook Classic: Not supported

  • [popover]

    Works in 3 of 21 · partial in 2 · not supported in 15 · 1 untested

    Outlook Classic: Not supported

  • [required]

    Works in 7 of 21 · partial in 1 · not supported in 12 · 1 untested

    Outlook Classic: Not supported

  • [role]

    Works in 14 of 21 · partial in 4 · not supported in 2 · 1 untested

    Outlook Classic: Not supported

  • [srcset]

    Works in 4 of 21 · not supported in 16 · 1 untested

    Outlook Classic: Not supported

  • [target]

    Works in 0 of 21 · partial in 8 · not supported in 12 · 1 untested

    Outlook Classic: Partial

  • [valign]

    Works in 20 of 21 · 1 untested

    Outlook Classic: Works

  • [width]

    Works in 18 of 21 · partial in 1 · not supported in 1 · 1 untested

    Outlook Classic: Partial

HTML & Email Structure 8
  • amp4email

    Works in 6 of 21 · not supported in 14 · 1 untested

    Outlook Classic: Not supported

  • anchor-links

    Works in 12 of 21 · partial in 1 · not supported in 7 · 1 untested

    Outlook Classic: Works

  • doctype

    Works in 13 of 21 · not supported in 7 · 1 untested

    Outlook Classic: Not supported

  • html-comments

    Works in 18 of 21 · 3 untested

    Outlook Classic: Works

  • html5-semantics

    Works in 6 of 21 · partial in 9 · not supported in 5 · 1 untested

    Outlook Classic: Not supported

  • image-maps

    Works in 15 of 21 · not supported in 5 · 1 untested

    Outlook Classic: Not supported

  • mailto-links

    Works in 17 of 21 · partial in 3 · 1 untested

    Outlook Classic: Works

  • meta-color-scheme

    Works in 2 of 21 · partial in 2 · not supported in 16 · 1 untested

    Outlook Classic: Not supported

CSS At-Rules 10
  • @font-face

    Works in 6 of 21 · not supported in 15

    Outlook Classic: Not supported

  • @import

    Works in 4 of 21 · not supported in 17

    Outlook Classic: Works

  • @keyframes

    Works in 7 of 21 · partial in 1 · not supported in 13

    Outlook Classic: Not supported

  • @media

    Works in 5 of 21 · partial in 14 · not supported in 2

    Outlook Classic: Not supported

  • @media device-pixel-ratio

    Works in 10 of 21 · not supported in 10 · 1 untested

    Outlook Classic: Not supported

  • @media hover

    Works in 9 of 21 · not supported in 8 · 4 untested

    Outlook Classic: Not supported

  • @media orientation

    Works in 11 of 21 · partial in 1 · not supported in 8 · 1 untested

    Outlook Classic: Not supported

  • @media prefers-color-scheme

    Works in 9 of 21 · not supported in 11 · 1 untested

    Outlook Classic: Not supported

  • @media prefers-reduced-motion

    Works in 9 of 21 · partial in 1 · not supported in 10 · 1 untested

    Outlook Classic: Not supported

  • @supports

    Works in 9 of 21 · not supported in 12

    Outlook Classic: Not supported

Pseudo-Elements 6
  • ::after

    Works in 6 of 21 · partial in 4 · not supported in 10 · 1 untested

    Outlook Classic: Not supported

  • ::before

    Works in 6 of 21 · partial in 4 · not supported in 10 · 1 untested

    Outlook Classic: Not supported

  • ::first-letter

    Works in 10 of 21 · partial in 4 · not supported in 6 · 1 untested

    Outlook Classic: Not supported

  • ::first-line

    Works in 10 of 21 · partial in 4 · not supported in 6 · 1 untested

    Outlook Classic: Not supported

  • ::marker

    Works in 10 of 21 · not supported in 10 · 1 untested

    Outlook Classic: Not supported

  • ::placeholder

    Works in 9 of 21 · partial in 4 · not supported in 7 · 1 untested

    Outlook Classic: Not supported

Pseudo-Classes & Selectors 34
  • :adjacent-sibling

    Works in 16 of 21 · partial in 2 · not supported in 2 · 1 untested

    Outlook Classic: Not supported

  • :attribute-selector

    Works in 6 of 21 · partial in 12 · not supported in 2 · 1 untested

    Outlook Classic: Not supported

  • :chaining

    Works in 14 of 21 · partial in 2 · not supported in 4 · 1 untested

    Outlook Classic: Not supported

  • :checked

    Works in 9 of 21 · partial in 5 · not supported in 6 · 1 untested

    Outlook Classic: Not supported

  • :child-combinator

    Works in 16 of 21 · partial in 2 · not supported in 2 · 1 untested

    Outlook Classic: Not supported

  • :class-selector

    Works in 17 of 21 · partial in 2 · not supported in 1 · 1 untested

    Outlook Classic: Works

  • :descendant-combinator

    Works in 17 of 21 · partial in 2 · not supported in 1 · 1 untested

    Outlook Classic: Works

  • :first-child

    Works in 12 of 21 · partial in 3 · not supported in 5 · 1 untested

    Outlook Classic: Not supported

  • :first-of-type

    Works in 12 of 21 · partial in 3 · not supported in 5 · 1 untested

    Outlook Classic: Not supported

  • :focus

    Works in 10 of 21 · partial in 3 · not supported in 7 · 1 untested

    Outlook Classic: Not supported

  • :focus-visible

    Works in 6 of 21 · partial in 4 · not supported in 4 · 7 untested

    Outlook Classic: Not supported

  • :focus-within

    Works in 6 of 21 · partial in 2 · not supported in 6 · 7 untested

    Outlook Classic: Not supported

  • :general-sibling

    Works in 16 of 21 · partial in 2 · not supported in 2 · 1 untested

    Outlook Classic: Not supported

  • :grouping

    Works in 17 of 21 · partial in 2 · not supported in 1 · 1 untested

    Outlook Classic: Works

  • :has

    Works in 5 of 21 · not supported in 15 · 1 untested

    Outlook Classic: Not supported

  • :hover

    Works in 12 of 21 · partial in 4 · not supported in 4 · 1 untested

    Outlook Classic: Not supported

  • :id-selector

    Works in 17 of 21 · partial in 2 · not supported in 1 · 1 untested

    Outlook Classic: Works

  • :lang

    Works in 6 of 21 · not supported in 11 · 4 untested

    Outlook Classic: Not supported

  • :last-child

    Works in 12 of 21 · partial in 3 · not supported in 5 · 1 untested

    Outlook Classic: Not supported

  • :last-of-type

    Works in 12 of 21 · partial in 3 · not supported in 5 · 1 untested

    Outlook Classic: Not supported

  • :link

    Works in 13 of 21 · partial in 3 · not supported in 4 · 1 untested

    Outlook Classic: Works

  • :not

    Works in 6 of 21 · not supported in 14 · 1 untested

    Outlook Classic: Not supported

  • :nth-child

    Works in 6 of 21 · not supported in 14 · 1 untested

    Outlook Classic: Not supported

  • :nth-last-child

    Works in 6 of 21 · not supported in 14 · 1 untested

    Outlook Classic: Not supported

  • :nth-of-type

    Works in 6 of 21 · not supported in 14 · 1 untested

    Outlook Classic: Not supported

  • :only-child

    Works in 12 of 21 · partial in 3 · not supported in 5 · 1 untested

    Outlook Classic: Not supported

  • :only-of-type

    Works in 12 of 21 · partial in 3 · not supported in 5 · 1 untested

    Outlook Classic: Not supported

  • :target

    Works in 7 of 21 · partial in 3 · not supported in 10 · 1 untested

    Outlook Classic: Not supported

  • :type-selector

    Works in 17 of 21 · partial in 2 · not supported in 1 · 1 untested

    Outlook Classic: Works

  • :universal-selector

    Works in 16 of 21 · partial in 2 · not supported in 2 · 1 untested

    Outlook Classic: Not supported

  • :visited

    Works in 8 of 21 · partial in 3 · not supported in 9 · 1 untested

    Outlook Classic: Not supported

  • pseudo-class-active

    Works in 8 of 21 · partial in 4 · not supported in 8 · 1 untested

    Outlook Classic: Not supported

  • pseudo-class-default

    Works in 10 of 21 · partial in 2 · not supported in 5 · 4 untested

    Outlook Classic: Not supported

  • pseudo-class-nth-last-of-type

    Works in 6 of 21 · not supported in 14 · 1 untested

    Outlook Classic: Not supported

CSS Functions 8
  • calc

    Works in 8 of 21 · partial in 2 · not supported in 10 · 1 untested

    Outlook Classic: Not supported

  • clamp

    Works in 6 of 21 · partial in 3 · not supported in 11 · 1 untested

    Outlook Classic: Not supported

  • conic-gradient

    Works in 6 of 21 · partial in 1 · not supported in 13 · 1 untested

    Outlook Classic: Not supported

  • fit-content

    Works in 11 of 21 · partial in 3 · not supported in 6 · 1 untested

    Outlook Classic: Not supported

  • linear-gradient

    Works in 9 of 21 · partial in 2 · not supported in 10

    Outlook Classic: Not supported

  • max

    Works in 6 of 21 · partial in 3 · not supported in 11 · 1 untested

    Outlook Classic: Not supported

  • min

    Works in 6 of 21 · partial in 3 · not supported in 11 · 1 untested

    Outlook Classic: Not supported

  • radial-gradient

    Works in 10 of 21 · partial in 1 · not supported in 10

    Outlook Classic: Not supported

CSS Properties 164
  • !important

    Works in 11 of 21 · partial in 9 · 1 untested

    Outlook Classic: Partial

  • accent-color

    Works in 5 of 21 · not supported in 15 · 1 untested

    Outlook Classic: Not supported

  • align-items

    Works in 13 of 21 · not supported in 8

    Outlook Classic: Not supported

  • animation

    Works in 5 of 21 · partial in 1 · not supported in 15

    Outlook Classic: Not supported Fix for Outlook Classic

  • aspect-ratio

    Works in 5 of 21 · not supported in 16

    Outlook Classic: Not supported

  • backdrop-filter

    Works in 6 of 21 · not supported in 12 · 3 untested

    Outlook Classic: Not supported

  • background

    Works in 16 of 21 · partial in 5

    Outlook Classic: Partial

  • background-blend-mode

    Works in 13 of 21 · partial in 2 · not supported in 5 · 1 untested

    Outlook Classic: Not supported

  • background-clip

    Works in 14 of 21 · partial in 2 · not supported in 5

    Outlook Classic: Not supported

  • background-color

    Works in 21 of 21

    Outlook Classic: Works

  • background-image

    Works in 16 of 21 · partial in 4 · not supported in 1

    Outlook Classic: Not supported

  • background-origin

    Works in 14 of 21 · partial in 2 · not supported in 5

    Outlook Classic: Not supported

  • background-position

    Works in 20 of 21 · not supported in 1

    Outlook Classic: Not supported

  • background-repeat

    Works in 20 of 21 · not supported in 1

    Outlook Classic: Not supported

  • background-size

    Works in 17 of 21 · partial in 3 · not supported in 1

    Outlook Classic: Not supported

  • bimi

    Works in 9 of 21 · not supported in 11 · 1 untested

    Outlook Classic: Not supported

  • block-size

    Works in 7 of 21 · not supported in 13 · 1 untested

    Outlook Classic: Not supported

  • border

    Works in 20 of 21 · partial in 1

    Outlook Classic: Partial

  • border-collapse

    Works in 19 of 21 · 2 untested

    Outlook Classic: Works

  • border-image

    Works in 7 of 21 · not supported in 13 · 1 untested

    Outlook Classic: Not supported

  • border-inline

    Works in 3 of 21 · not supported in 14 · 4 untested

    Outlook Classic: Not supported

  • border-inline-individual

    Works in 3 of 21 · partial in 1 · not supported in 13 · 4 untested

    Outlook Classic: Not supported

  • border-inline-longhand

    Works in 4 of 21 · not supported in 13 · 4 untested

    Outlook Classic: Not supported

  • border-radius

    Works in 16 of 21 · partial in 4 · not supported in 1

    Outlook Classic: Not supported Fix for Outlook Classic

  • border-radius-logical

    Works in 3 of 21 · not supported in 14 · 4 untested

    Outlook Classic: Not supported

  • border-spacing

    Works in 17 of 21 · not supported in 2 · 2 untested

    Outlook Classic: Not supported Fix for Outlook Classic

  • bottom

    Works in 11 of 21 · partial in 1 · not supported in 8 · 1 untested

    Outlook Classic: Not supported

  • box-shadow

    Works in 14 of 21 · partial in 2 · not supported in 5

    Outlook Classic: Not supported

  • box-sizing

    Works in 16 of 21 · not supported in 5

    Outlook Classic: Not supported

  • caption-side

    Works in 20 of 21 · not supported in 1

    Outlook Classic: Not supported

  • clear

    Works in 9 of 21 · partial in 6 · not supported in 1 · 5 untested

    Outlook Classic: Not supported

  • clip-path

    Works in 8 of 21 · not supported in 13

    Outlook Classic: Not supported

  • color

    Works in 21 of 21

    Outlook Classic: Works

  • color-scheme

    Works in 4 of 21 · not supported in 16 · 1 untested

    Outlook Classic: Not supported

  • column-count

    Works in 16 of 21 · not supported in 5

    Outlook Classic: Not supported

  • columns

    Works in 16 of 21 · not supported in 5

    Outlook Classic: Not supported

  • css-comments

    Works in 14 of 21 · partial in 4 · 3 untested

    Outlook Classic: Works

  • cursor

    Works in 2 of 21 · partial in 4 · not supported in 10 · 5 untested

    Outlook Classic: Untested

  • custom-properties

    Works in 6 of 21 · not supported in 14 · 1 untested

    Outlook Classic: Not supported

  • direction

    Works in 21 of 21

    Outlook Classic: Works

  • display

    Works in 13 of 21 · partial in 8

    Outlook Classic: Partial

  • display:flex

    Works in 18 of 21 · partial in 2 · not supported in 1

    Outlook Classic: Not supported Fix for Outlook Classic

  • display:grid

    Works in 18 of 21 · partial in 2 · not supported in 1

    Outlook Classic: Not supported Fix for Outlook Classic

  • display:none

    Works in 20 of 21 · partial in 1

    Outlook Classic: Partial

  • empty-cells

    Works in 14 of 21 · not supported in 4 · 3 untested

    Outlook Classic: Not supported

  • filter

    Works in 7 of 21 · not supported in 14

    Outlook Classic: Not supported

  • flex

    Works in 13 of 21 · not supported in 8

    Outlook Classic: Not supported

  • flex-basis

    Works in 13 of 21 · not supported in 8

    Outlook Classic: Not supported

  • flex-direction

    Works in 12 of 21 · not supported in 9

    Outlook Classic: Not supported

  • flex-wrap

    Works in 13 of 21 · not supported in 8

    Outlook Classic: Not supported

  • float

    Works in 14 of 21 · partial in 6 · not supported in 1

    Outlook Classic: Not supported

  • font

    Works in 20 of 21 · 1 untested

    Outlook Classic: Works

  • font-family

    Works in 21 of 21

    Outlook Classic: Works

  • font-kerning

    Works in 13 of 21 · not supported in 5 · 3 untested

    Outlook Classic: Not supported

  • font-size

    Works in 13 of 21 · partial in 6 · 2 untested

    Outlook Classic: Partial

  • font-size-adjust

    Works in 10 of 21 · partial in 5 · not supported in 1 · 5 untested

    Outlook Classic: Not supported

  • font-stretch

    Works in 10 of 21 · not supported in 8 · 3 untested

    Outlook Classic: Not supported

  • font-weight

    Works in 16 of 21 · partial in 5

    Outlook Classic: Partial

  • gap

    Works in 7 of 21 · partial in 9 · not supported in 5

    Outlook Classic: Not supported Fix for Outlook Classic

  • grid-template-columns

    Works in 7 of 21 · partial in 1 · not supported in 13

    Outlook Classic: Not supported

  • height

    Works in 16 of 21 · partial in 1 · not supported in 4

    Outlook Classic: Partial

  • hyphenate-character

    Works in 4 of 21 · not supported in 13 · 4 untested

    Outlook Classic: Not supported

  • hyphenate-limit-chars

    Works in 1 of 21 · not supported in 17 · 3 untested

    Outlook Classic: Not supported

  • hyphens

    Works in 4 of 21 · not supported in 13 · 4 untested

    Outlook Classic: Not supported

  • inert

    Works in 3 of 21 · not supported in 14 · 4 untested

    Outlook Classic: Not supported

  • inline-size

    Works in 4 of 21 · not supported in 16 · 1 untested

    Outlook Classic: Not supported

  • inset

    Works in 3 of 21 · not supported in 15 · 3 untested

    Outlook Classic: Not supported

  • justify-content

    Works in 13 of 21 · not supported in 8

    Outlook Classic: Not supported

  • left

    Works in 11 of 21 · partial in 1 · not supported in 8 · 1 untested

    Outlook Classic: Not supported

  • letter-spacing

    Works in 20 of 21 · partial in 1

    Outlook Classic: Partial

  • light-dark

    Works in 3 of 21 · partial in 3 · not supported in 11 · 4 untested

    Outlook Classic: Not supported

  • line-height

    Works in 20 of 21 · partial in 1

    Outlook Classic: Partial

  • list-style

    Works in 11 of 21 · partial in 9 · not supported in 1

    Outlook Classic: Partial

  • list-style-image

    Works in 6 of 21 · not supported in 14 · 1 untested

    Outlook Classic: Not supported

  • list-style-position

    Works in 19 of 21 · not supported in 1 · 1 untested

    Outlook Classic: Not supported

  • list-style-type

    Works in 21 of 21

    Outlook Classic: Works

  • margin

    Works in 8 of 21 · partial in 13

    Outlook Classic: Partial

  • margin-block-start-end

    Works in 4 of 21 · not supported in 13 · 4 untested

    Outlook Classic: Not supported

  • margin-inline-block

    Works in 6 of 21 · not supported in 14 · 1 untested

    Outlook Classic: Not supported

  • margin-inline-start-end

    Works in 4 of 21 · not supported in 13 · 4 untested

    Outlook Classic: Not supported

  • mask-image

    Works in 4 of 21 · partial in 1 · not supported in 12 · 4 untested

    Outlook Classic: Not supported

  • max-block-size

    Works in 5 of 21 · not supported in 12 · 4 untested

    Outlook Classic: Not supported

  • max-height

    Works in 20 of 21 · not supported in 1

    Outlook Classic: Not supported Fix for Outlook Classic

  • max-inline-size

    Works in 4 of 21 · not supported in 13 · 4 untested

    Outlook Classic: Not supported

  • max-width

    Works in 20 of 21 · partial in 1

    Outlook Classic: Partial Fix for Outlook Classic

  • min-block-size

    Works in 4 of 21 · not supported in 13 · 4 untested

    Outlook Classic: Not supported

  • min-height

    Works in 19 of 21 · not supported in 2

    Outlook Classic: Not supported

  • min-inline-size

    Works in 5 of 21 · not supported in 12 · 4 untested

    Outlook Classic: Not supported

  • min-width

    Works in 20 of 21 · not supported in 1

    Outlook Classic: Not supported

  • mix-blend-mode

    Works in 13 of 21 · partial in 2 · not supported in 6

    Outlook Classic: Not supported

  • modern-color

    Works in 4 of 21 · not supported in 16 · 1 untested

    Outlook Classic: Not supported

  • nesting

    Works in 2 of 21 · partial in 3 · not supported in 13 · 3 untested

    Outlook Classic: Not supported

  • object-fit

    Works in 14 of 21 · partial in 2 · not supported in 5

    Outlook Classic: Not supported

  • object-position

    Works in 14 of 21 · partial in 2 · not supported in 5

    Outlook Classic: Not supported

  • opacity

    Works in 19 of 21 · not supported in 2

    Outlook Classic: Not supported Fix for Outlook Classic

  • orphans

    Works in 10 of 21 · not supported in 8 · 3 untested

    Outlook Classic: Not supported

  • outline

    Works in 20 of 21 · not supported in 1

    Outlook Classic: Not supported

  • outline-offset

    Works in 7 of 21 · not supported in 13 · 1 untested

    Outlook Classic: Not supported

  • overflow

    Works in 4 of 21 · partial in 16 · not supported in 1

    Outlook Classic: Not supported

  • overflow-wrap

    Works in 2 of 21 · partial in 3 · not supported in 13 · 3 untested

    Outlook Classic: Not supported Fix for Outlook Classic

  • padding

    Works in 20 of 21 · partial in 1

    Outlook Classic: Partial Fix for Outlook Classic

  • padding-block-start-end

    Works in 4 of 21 · not supported in 13 · 4 untested

    Outlook Classic: Not supported

  • padding-inline-block

    Works in 3 of 21 · not supported in 14 · 4 untested

    Outlook Classic: Not supported

  • padding-inline-start-end

    Works in 4 of 21 · not supported in 13 · 4 untested

    Outlook Classic: Not supported

  • position

    Works in 2 of 21 · partial in 14 · not supported in 5

    Outlook Classic: Not supported Fix for Outlook Classic

  • resize

    Works in 1 of 21 · partial in 1 · not supported in 16 · 3 untested

    Outlook Classic: Not supported

  • rgb

    Works in 12 of 21 · partial in 8 · 1 untested

    Outlook Classic: Partial

  • rgba

    Works in 12 of 21 · partial in 7 · not supported in 1 · 1 untested

    Outlook Classic: Not supported

  • right

    Works in 11 of 21 · partial in 1 · not supported in 8 · 1 untested

    Outlook Classic: Not supported

  • scroll-snap

    Works in 6 of 21 · not supported in 14 · 1 untested

    Outlook Classic: Not supported

  • shape-margin

    Works in 6 of 21 · not supported in 12 · 3 untested

    Outlook Classic: Not supported

  • shape-outside

    Works in 6 of 21 · not supported in 12 · 3 untested

    Outlook Classic: Not supported

  • system-ui

    Works in 12 of 21 · partial in 7 · not supported in 1 · 1 untested

    Outlook Classic: Not supported

  • tab-size

    Works in 8 of 21 · not supported in 9 · 4 untested

    Outlook Classic: Not supported

  • table-layout

    Works in 16 of 21 · not supported in 2 · 3 untested

    Outlook Classic: Not supported

  • text-align

    Works in 13 of 21 · partial in 8

    Outlook Classic: Partial

  • text-align-last

    Works in 7 of 21 · not supported in 10 · 4 untested

    Outlook Classic: Not supported

  • text-decoration

    Works in 14 of 21 · partial in 6 · not supported in 1

    Outlook Classic: Partial

  • text-decoration-color

    Works in 17 of 21 · partial in 2 · not supported in 1 · 1 untested

    Outlook Classic: Not supported

  • text-decoration-line

    Works in 16 of 21 · not supported in 2 · 3 untested

    Outlook Classic: Not supported

  • text-decoration-skip-ink

    Works in 7 of 21 · not supported in 13 · 1 untested

    Outlook Classic: Not supported

  • text-decoration-style

    Works in 16 of 21 · not supported in 2 · 3 untested

    Outlook Classic: Not supported

  • text-decoration-thickness

    Works in 7 of 21 · not supported in 13 · 1 untested

    Outlook Classic: Not supported

  • text-emphasis

    Works in 9 of 21 · not supported in 8 · 4 untested

    Outlook Classic: Not supported

  • text-emphasis-position

    Works in 4 of 21 · not supported in 13 · 4 untested

    Outlook Classic: Not supported

  • text-indent

    Works in 13 of 21 · partial in 8

    Outlook Classic: Works

  • text-justify

    Works in 0 of 21 · partial in 4 · not supported in 13 · 4 untested

    Outlook Classic: Not supported

  • text-orientation

    Works in 13 of 21 · not supported in 5 · 3 untested

    Outlook Classic: Not supported

  • text-overflow

    Works in 13 of 21 · partial in 2 · not supported in 6

    Outlook Classic: Not supported

  • text-shadow

    Works in 12 of 21 · not supported in 9

    Outlook Classic: Not supported Fix for Outlook Classic

  • text-transform

    Works in 20 of 21 · partial in 1

    Outlook Classic: Partial

  • text-underline-offset

    Works in 7 of 21 · not supported in 13 · 1 untested

    Outlook Classic: Not supported

  • text-underline-position

    Works in 8 of 21 · partial in 4 · not supported in 6 · 3 untested

    Outlook Classic: Not supported

  • text-wrap

    Works in 4 of 21 · not supported in 13 · 4 untested

    Outlook Classic: Not supported

  • top

    Works in 11 of 21 · partial in 1 · not supported in 8 · 1 untested

    Outlook Classic: Not supported

  • transform

    Works in 7 of 21 · partial in 1 · not supported in 13

    Outlook Classic: Not supported Fix for Outlook Classic

  • transition

    Works in 4 of 21 · partial in 7 · not supported in 10

    Outlook Classic: Not supported

  • unit-ch

    Works in 15 of 21 · not supported in 5 · 1 untested

    Outlook Classic: Not supported

  • unit-cm

    Works in 20 of 21 · 1 untested

    Outlook Classic: Works

  • unit-em

    Works in 20 of 21 · 1 untested

    Outlook Classic: Works

  • unit-ex

    Works in 20 of 21 · 1 untested

    Outlook Classic: Works

  • unit-in

    Works in 20 of 21 · 1 untested

    Outlook Classic: Works

  • unit-initial

    Works in 12 of 21 · partial in 3 · not supported in 5 · 1 untested

    Outlook Classic: Not supported

  • unit-mm

    Works in 20 of 21 · 1 untested

    Outlook Classic: Works

  • unit-pc

    Works in 20 of 21 · 1 untested

    Outlook Classic: Works

  • unit-percent

    Works in 20 of 21 · 1 untested

    Outlook Classic: Works

  • unit-pt

    Works in 20 of 21 · 1 untested

    Outlook Classic: Works

  • unit-px

    Works in 20 of 21 · 1 untested

    Outlook Classic: Works

  • unit-rem

    Works in 15 of 21 · not supported in 5 · 1 untested

    Outlook Classic: Not supported

  • unit-vh

    Works in 17 of 21 · partial in 1 · not supported in 2 · 1 untested

    Outlook Classic: Not supported

  • unit-vmax

    Works in 15 of 21 · not supported in 5 · 1 untested

    Outlook Classic: Not supported

  • unit-vmin

    Works in 15 of 21 · not supported in 5 · 1 untested

    Outlook Classic: Not supported

  • unit-vw

    Works in 18 of 21 · not supported in 2 · 1 untested

    Outlook Classic: Not supported

  • user-select

    Works in 3 of 21 · partial in 2 · not supported in 13 · 3 untested

    Outlook Classic: Not supported

  • vertical-align

    Works in 21 of 21

    Outlook Classic: Works

  • visibility

    Works in 13 of 21 · not supported in 8

    Outlook Classic: Not supported Fix for Outlook Classic

  • white-space

    Works in 15 of 21 · partial in 4 · not supported in 2

    Outlook Classic: Not supported

  • white-space-collapse

    Works in 4 of 21 · not supported in 13 · 4 untested

    Outlook Classic: Not supported

  • widows

    Works in 10 of 21 · not supported in 8 · 3 untested

    Outlook Classic: Not supported

  • width

    Works in 20 of 21 · partial in 1

    Outlook Classic: Partial

  • word-break

    Works in 4 of 21 · partial in 12 · not supported in 5

    Outlook Classic: Not supported Fix for Outlook Classic

  • word-spacing

    Works in 14 of 21 · partial in 3 · not supported in 2 · 2 untested

    Outlook Classic: Not supported

  • writing-mode

    Works in 13 of 21 · partial in 2 · not supported in 6

    Outlook Classic: Not supported

  • z-index

    Works in 17 of 21 · not supported in 4

    Outlook Classic: Not supported

The same Emailens probe in two real installs

border-radius is not supported in Outlook Classic. Screenshots of our border-radius probe, taken 14 Oct 2026. Where it is supported you should see: rounded corners.

Outlook 2016 (Windows), real install · counted as Outlook Classic
The Emailens probe for border-radius on a real Outlook 2016 (Windows)
Apple Mail (macOS), real install · counted as Apple Mail
The Emailens probe for border-radius on a real Apple Mail (macOS)

border-radius in Outlook Classic, with the fix →

Where each feature works

Features by how many of the 21 clients they work in. Grey is untested, not broken.

clients a feature works in

36 work in 20 of 21. The one gap: untested in Superhuman for 22, partial in Outlook Classic for 8, not supported in Outlook Classic for 6.

Each client, the same way

All 300 features in each client. Grey is untested, not broken.

  • Gmail

    Works 152 · Partial 17 · Not supported 131 · Untested 0 · of 300

  • Gmail Android

    Works 109 · Partial 66 · Not supported 125 · Untested 0 · of 300

  • Gmail iOS

    Works 106 · Partial 60 · Not supported 134 · Untested 0 · of 300

  • Outlook 365

    Works 169 · Partial 34 · Not supported 97 · Untested 0 · of 300

  • Outlook (New)

    Works 168 · Partial 34 · Not supported 98 · Untested 0 · of 300

  • Outlook Classic

    Works 51 · Partial 26 · Not supported 222 · Untested 1 · of 300

  • Outlook iOS

    Works 184 · Partial 19 · Not supported 94 · Untested 3 · of 300

  • Outlook Android

    Works 179 · Partial 18 · Not supported 102 · Untested 1 · of 300

  • Outlook for Mac

    Works 170 · Partial 37 · Not supported 92 · Untested 1 · of 300

  • Apple Mail

    Works 280 · Partial 14 · Not supported 6 · Untested 0 · of 300

  • Apple Mail iOS

    Works 275 · Partial 12 · Not supported 11 · Untested 2 · of 300

  • Yahoo Mail

    Works 126 · Partial 32 · Not supported 142 · Untested 0 · of 300

  • Yahoo Mail Android

    Works 118 · Partial 31 · Not supported 150 · Untested 1 · of 300

  • Yahoo Mail iOS

    Works 120 · Partial 28 · Not supported 150 · Untested 2 · of 300

  • Samsung Mail

    Works 246 · Partial 25 · Not supported 26 · Untested 3 · of 300

  • Thunderbird

    Works 228 · Partial 12 · Not supported 21 · Untested 39 · of 300 · Tested on fewer than 270 of 300 features

  • HEY Mail

    Works 173 · Partial 10 · Not supported 53 · Untested 64 · of 300 · Tested on fewer than 270 of 300 features

  • Proton Mail

    Works 200 · Partial 18 · Not supported 82 · Untested 0 · of 300

  • AOL Mail

    Works 111 · Partial 28 · Not supported 159 · Untested 2 · of 300

  • Fastmail

    Works 193 · Partial 4 · Not supported 38 · Untested 65 · of 300 · Tested on fewer than 270 of 300 features

  • Superhuman

    Works 86 · Partial 5 · Not supported 6 · Untested 203 · of 300 · Tested on fewer than 270 of 300 features

Questions

How many features work in every email client?
6 of 300 work in all 21 clients. 28 more work in every client that has tested them; the rest of their cells are untested, not broken. 15 more work at least partly in all 21.
Is any of this measured in real email clients?
Partly. Support levels are caniemail's documented results, mapped onto 21 clients by @emailens/engine. For 24 features we ran the Emailens probe on 11 real installs: 252 screenshots covering 5 of the 21 clients, on 14 Oct 2026. A probe is a single-feature test strip, not a full email. Those feature pages show each capture beside our live preview of the same client.
Where does the data come from, and how current is it?
Support levels come from caniemail.com (MIT), mapped onto 21 clients by @emailens/engine 0.18.22. The Outlook (New) cells are the engine's mapping, not a caniemail column. The data last changed on 10 Nov 2026: that is when the matrix last changed, not when features were tested. caniemail's own tests are dated per feature, from 28 Feb 2019 to 16 Sep 2026, and 286 of the 296 dated features were last tested more than a year before that date. Each feature page shows its own.

Your next question

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data last changed 10 Nov 2026 · Renderle, a daily game on this table