Email Client Compatibility

A reference of CSS and HTML support across four major email clients: Apple Mail, Gmail, Outlook and Yahoo. Data is sourced from caniemail.com. Apple Mail means macOS, Gmail means desktop webmail, Outlook means Windows (Word engine), and Yahoo means desktop webmail.

Support summary

The reference covers 173 features. Each is rated Supported, Partial or Not supported per client, with notes on some entries.

Client	Supported	Partial	Not supported	Share supported
Apple Mail	166	7	0	96%
Gmail	92	16	65	53%
Outlook	37	28	108	21%
Yahoo	91	24	58	53%

Categories

• CSS At-Rules: @font-face, @import, @keyframes, @media, @supports.
• CSS Properties: background, border, box model, layout (including flexbox and grid), positioning, text, list, table, animation, visual effects and others such as CSS variables and !important.
• CSS Selectors: basic selectors, combinators, pseudo-classes and pseudo-elements.
• CSS Functions & Values: calc(), clamp(), min()/max(), colors, gradients and units.
• HTML Elements: head, structure, media, interactive (forms and inputs) and semantic elements.
• HTML Attributes: layout, sizing, table, accessibility, media and performance attributes.
• Image Formats: JPG, PNG, animated GIF, WebP, AVIF, SVG, Base64 and APNG.

Sample rows

Feature	Apple Mail	Gmail	Outlook	Yahoo
@media	Yes	Partial	No	Partial
@keyframes	Yes	No	No	Yes
background-image	Yes	Yes	No	Partial
border-radius	Yes	Yes	No	Partial
display: flex	Yes	Yes	No	Yes
display: grid	Yes	No	No	No
position	Partial	No	No	Partial
CSS variables (--*)	Yes	No	No	No
:hover	Yes	Yes	No	Yes
:checked	Yes	No	No	Yes
linear-gradient()	Yes	No	No	No
<style>	Yes	Partial	Partial	Yes
<video>	Yes	No	No	No
<input type="checkbox">	Yes	Yes	No	Yes
WebP	Yes	Partial	No	Yes
SVG (as <img> src)	Yes	No	No	Yes

Notes on some entries explain partial support. For example, @media is supported in the Gmail app but stripped in Gmail web, and Outlook needs VML for background images.

Using the reference

Search by property or element name, filter by category, and filter by support level, either across any client or for one specific client. To see these rules applied to your own HTML, use the Email Render Simulator. For dozens of additional clients, including Samsung Mail, Outlook Mac, Thunderbird, AOL and Proton Mail, see caniemail.com.