feat: use Next.js 16

[gabrielmfern]

Updates the react.email website and the preview server to use Next.js 16. With this we're also moving to turbopack.

The only exception for not using turbopack is when building in the email build command. The main reason is that turbopack doesn't handle modules that it can't find the same exact way as webpack, which makes it just error building the preview server when it can't find the imports:

react-email/packages/tailwind/src/utils/react/is-component.ts

Lines 1 to 11 in ffe1dbe

	import { Body } from '@react-email/body';
	import { Button } from '@react-email/button';
	import { CodeBlock } from '@react-email/code-block';
	import { CodeInline } from '@react-email/code-inline';
	import { Container } from '@react-email/container';
	import { Heading } from '@react-email/heading';
	import { Hr } from '@react-email/hr';
	import { Img } from '@react-email/img';
	import { Link } from '@react-email/link';
	import { Preview } from '@react-email/preview';
	import { Text } from '@react-email/text';

To circumvent this, while we don't yet completely remove the npm install step from email build we'll have to stick to webpack there. We could also have @react-email/components as a dependency of the preview server to fix this, but I'm not sure what kind of impact on stability that could have - as in, conflicts with the ones installed by the user.

---

Summary by cubic

Upgrade workspace to Next.js 16 and enable Turbopack by default for faster dev/build, while keeping webpack for the email build command to avoid module resolution errors in preview builds. No breaking changes to the Tailwind API; minor helpers are now exported for better tree-shaking.

• Dependencies

  • Bumped Next to 16.0.1 across apps, packages, and examples (requires Node >= 20.9.0).
  • Moved configs to Next 16 conventions: next.config.ts (ESM) with serverExternalPackages: ['esbuild'] and updated next-env.d.ts import form.
  • email build uses next build --webpack to match webpack’s missing-module behavior and keep preview builds stable.

• Refactors

  • Tailwind: extracted sanitizeStyleSheet and inlineStyles as standalone exports to improve tree-shaking and reduce bundle size.

^{Written for commit ab5c789. Summary will update automatically on new commits.}

[changeset-bot]

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Latest commit: ab5c789

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[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Preview	Comments	Updated (UTC)
react-email	Ready	Preview	Comment	Oct 30, 2025 4:05pm
react-email-demo	Ready	Preview	Comment	Oct 30, 2025 4:05pm

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/resend/react-email/@react-email/preview-server@2613

npm i https://pkg.pr.new/resend/react-email@2613

npm i https://pkg.pr.new/resend/react-email/@react-email/tailwind@2613

commit: ab5c789

[cubic-dev-ai]

1 issue found across 16 files

Prompt for AI agents (all 1 issues)

Understand the root cause of the following 1 issues and fix them.


<file name="packages/react-email/package.json">

<violation number="1" location="packages/react-email/package.json:53">
Upgrading to Next 16.0.1 requires raising the package’s Node engine range to meet Next’s &gt;=20.9.0 requirement; leaving `engines.node` at &gt;=18.0.0 advertises support for versions where the preview tooling will now fail.</violation>
</file>

_{React with 👍 or 👎 to teach cubic. Mention @cubic-dev-ai to give feedback, ask questions, or re-run the review.}

[socket-security]

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	debounce@​2.0.0

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