HTML Elements

<bdi>

HTML element · 4 supported, 0 partial, 10 unsupported across 15 clients

The <bdi> element isolates a span of text whose directionality may differ from its surroundings. It is most useful in mixed-direction content (English + Arabic, Hebrew + English) but email client support is uneven. Modern WebKit clients honor it; Outlook and many older clients treat it as a generic <span>.

Client Support

Client	Category	Engine	Support
Gmail	webmail	Gmail Web	Unsupported
Gmail Android	mobile	Gmail Mobile	Unsupported
Gmail iOS	mobile	Gmail Mobile	Unsupported
Outlook 365	webmail	Outlook Web	Unsupported
Outlook (New)	desktop	Outlook Web	Unsupported
Outlook Classic	desktop	Microsoft Word	Unsupported
Outlook iOS	mobile	Outlook Mobile	Unsupported
Outlook Android	mobile	Outlook Mobile	Unsupported
Apple Mail	desktop	WebKit	Supported
Apple Mail iOS	mobile	WebKit	Supported
Yahoo Mail	webmail	Yahoo	Unsupported
Samsung Mail	mobile	Samsung	Supported
Thunderbird	desktop	Gecko	Supported
HEY Mail	webmail	WebKit	Unsupported
Superhuman	desktop	Blink	Unknown

Client-by-client behaviour for <bdi>

Fully supports <bdi> (4): Apple Mail, Apple Mail iOS, Samsung Mail, Thunderbird.

No support (10): Gmail, Gmail Android, Gmail iOS, Outlook 365, Outlook (New), Outlook Classic, Outlook iOS, Outlook Android, Yahoo Mail, HEY Mail. Plan fallbacks for these clients before relying on <bdi> in production sends.

Behaviour unverified in: Superhuman.

When to use <bdi> in email

Embedding user-generated names in a localized email where direction may be unknown.
Mixing English brand identifiers within Arabic body copy.
Editorial content that quotes right-to-left strings inside left-to-right paragraphs.

Rendering behaviour and edge cases

Apple Mail and modern Chromium-based Gmail honor <bdi> directionality isolation.
Outlook on Windows treats <bdi> as a regular inline element.
<bdi> is purely semantic — visual results match <span> in non-supporting clients.

Recommended fallback strategy

Use <bdi> liberally in mixed-direction content as a no-cost progressive enhancement. For visually critical bidi handling, also set explicit dir attributes on the surrounding elements to give clients the strongest possible directional signal.