CSS property · 10 real installs 14 Oct 2026 · data last changed 10 Nov 2026

word-break in email clients

Works in 4 of 21. Not supported in Outlook Classic, Yahoo Mail, Yahoo Mail Android and 2 more. Partial in Gmail Android, Gmail iOS, Outlook 365 and 9 more.

Your reader in Outlook Classic sees the email without word-break, even if it looks right where you tested it.

caniemail (MIT) via @emailens/engine 0.18.22

The fix for Outlook Classic

Outlook Windows does not wrap a URL on word-break, word-wrap, or overflow-wrap. Insert  in a cell that has a width

after

8 lines

<table role="presentation" width="100%" cellpadding="0"
  cellspacing="0" border="0">
  <tr>
    <td width="100%">
      https://example.com/&#8203;very/&#8203;long/&#8203;url?token=&#8203;abc123def456
    </td>
  </tr>
</table>

Show the original

before

3 lines

<span style="word-break: break-all;">
  https://example.com/very/long/url?token=abc123def456
</span>

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word-break on 10 real installs

One Emailens probe, screenshotted on each install on 14 October 2026, next to our live preview of the same client. Where word-break is supported you should see: long word wraps inside the box.

The Emailens probe for word-break on a real Outlook 2019 (Windows) — Outlook Classic

The Emailens probe for word-break on a real Outlook 2016 (Windows) — Outlook Classic

The Emailens probe for word-break on a real Yahoo Mail — Yahoo Mail

The same probe in the Emailens live preview of Yahoo Mail — Yahoo Mail

The Emailens probe for word-break on a real Outlook.com — Outlook 365

The same probe in the Emailens live preview of Outlook 365 — Outlook 365

The Emailens probe for word-break on a real Apple Mail (macOS) — Apple Mail

The same probe in the Emailens live preview of Apple Mail — Apple Mail

The Emailens probe for word-break on a real Apple Mail (iPhone 13) — Apple Mail iOS

The same probe in the Emailens live preview of Apple Mail iOS — Apple Mail iOS

Also captured, not counted as evidence (3)

Outlook for Microsoft 365 · not mapped to an engine client yet Real screenshot
Outlook 2019 for Mac (legacy app) · not counted as Outlook for Mac Real screenshot
This is the legacy Outlook for Mac app. The new Outlook for Mac, which the table describes, drops gradients, grid sizing functions, var() and more.
Gmail (web) · not counted as Gmail Real screenshot
This Gmail install does not apply Gmail's sanitiser, so it shows more than real Gmail does.

Every account includes one free real-device check in classic Outlook, Outlook for Mac and Apple Mail, after you verify your email and run one preview, while this month's free capacity lasts. How real-device checks work →

All 21 clients, problems first

Client	Support
Outlook Classic	Not supported
Yahoo Mail	Not supported
Yahoo Mail Android	Not supported
Yahoo Mail iOS	Not supported
AOL Mail	Not supported
Gmail Android	Partial ^{See caveat 2}
Gmail iOS	Partial ^{See caveat 2}
Outlook 365	Partial ^{See caveat 2}
Outlook (New)	Partial ^{See caveat 2}
Outlook iOS	Partial ^{See caveat 2}
Outlook Android	Partial ^{See caveat 2}
Outlook for Mac	Partial ^{See caveat 2}
Apple Mail	Partial ^{See caveat 2}
Apple Mail iOS	Partial ^{See caveat 2}
Samsung Mail	Partial ^{See caveat 2}
HEY Mail	Partial ^{See caveat 3}
Proton Mail	Partial ^{See caveat 2}

Works in 4: Gmail, Thunderbird, Fastmail and 1 more. Show all

Client	Support
Gmail	Works ^{See caveat 1}
Thunderbird	Works
Fastmail	Works
Superhuman	Works

Caveats (3)

1. Gmail: Supported. But Gmail adds <wbr> every 30 characters.
2. Gmail Android, Gmail iOS, Outlook 365, Outlook (New), Outlook iOS, Outlook Android, Outlook for Mac, Apple Mail, Apple Mail iOS, Samsung Mail, Proton Mail: Buggy. Supported but a word-wrap:break-word is applied, making it look like break-all.
3. HEY Mail: Buggy. Every value is replaced by break-word.

Caveats as recorded by caniemail (MIT), one entry per wording.

How word-break behaves

The word-break property specifies how words should break when reaching the boundary of their containing block. In HTML email, unspaced text strings like long URLs, tracking links, order numbers, and promo codes frequently overflow table cells on mobile viewports, forcing horizontal scrollbars and breaking layout widths. Configuring robust word-breaking rules is essential for responsive email resilience.

Gmail supports word-break and automatically inserts invisible <wbr> tags every 30 characters in long uninterrupted strings.
Gmail Android, Gmail iOS, Outlook 365, and Apple Mail apply word-wrap: break-word behavior to word-break declarations, splitting words at the container boundary.
Yahoo Mail and AOL Mail do not support CSS word-break, allowing long strings to stretch parent containers horizontally.
HEY Mail automatically normalizes any word-break declaration to break-word.

Apply a multi-property defense on any container that may display long strings or URLs: word-break: break-word; overflow-wrap: break-word; word-wrap: break-word;. Additionally, insert HTML <wbr> (word break opportunity) tags or zero-width spaces () inside long URLs to ensure they wrap even in clients like Yahoo Mail that ignore CSS word-break declarations.

Questions

How do I prevent long URLs from breaking my email layout on mobile?

Combine word-break: break-word; overflow-wrap: break-word; word-wrap: break-word; on the parent cell, and insert <wbr> tags inside long unspaced links so clients like Yahoo Mail wrap safely.

Does Gmail support word-break?

Yes. Gmail supports word-break and inserts break opportunities every 30 characters. Gmail mobile apps support break-word behavior.

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