Choose MJML when your team wants a dedicated email markup language with explicit structural validation. Choose React Email when the application already uses React and you want to pass business data into reusable components. In either case, compiling HTML is one stage of email production; it does not establish how Gmail or Outlook will display the message.
We compiled the same synthetic invoice notification with both tools. Both preserved the intended name, amount and action URL when used correctly. An unescaped MJML interpolation changed the visible name, while React text children preserved it. MJML also rejected an invalid component hierarchy in strict mode but returned HTML and an error list in soft mode. Those results point to different controls to put in your build.
Two template-building approaches
| Tool | Authoring model | Control demonstrated locally | Important limit |
|---|---|---|---|
| MJML | Email-specific markup compiled to HTML | Strict validation rejected mj-text directly under mj-body | Interpolated strings still need appropriate escaping |
| React Email | React components rendered to HTML and plain text | String child preserved A&B <Finance>; plain text retained the action URL | Rendered output still needs real email-client checks |
MJML
MJML’s documentation defines email components and three validation levels. Soft validation is the documented default. In our MJML 5.4.1 test, we deliberately selected strict mode and awaited the compiler result. The valid hierarchy used mj-body, mj-section, mj-column and then mj-text or mj-button.
The negative control placed mj-text directly inside mj-body. Strict mode raised a validation error identifying the parent problem. Soft mode returned HTML plus one error. A build that merely checks for a nonempty HTML string could therefore accept a known structural error. Our practical recommendation is to fail the build on compiler errors, rather than treating generated output as proof of validity.
The strength is a specific authoring vocabulary and a validation gate an email-maintenance team can review. The tradeoff is another source format and an explicit boundary between trusted markup and business data. XML escaping for a text node and escaping for an attribute are separate requirements; the four replacements used in this small fixture are not a general URL-safety or untrusted-HTML policy.
React Email
React Email’s render utilities turn components into HTML and provide plain-text conversion. Our local implementation used React 19.3.1, @react-email/components 1.0.12 and @react-email/render 2.1.1. The current documentation also shows the umbrella react-email package, so keep installation and imports consistent with the version you choose.
We passed the name as a Text component’s string child and the action URL as a Button prop, without injecting HTML. The browser-parsed output contained the literal name A&B <Finance>, no finance element, and the exact expected href. The generated plain text contained the invoice number, USD amount and complete URL. That reduces a separate plain-text authoring task for this example; it does not prove every complex template converts acceptably.
This approach fits a React team that can own component tests and shared application data types. It does not remove the need to validate recipient data, allowed destinations, localization or missing fields. We did not run TypeScript type checks in this JavaScript fixture, and do not compare React’s type system with MJML’s structural validator.
The notification we actually compiled
The input was invoice INV-0042, amount USD 125.00, recipient name A&B <Finance> and action URL below:
https://example.com/invoices/INV-0042?source=email&mode=viewThis deliberately puts ampersands and angle brackets at the boundary between data and markup. example.com was a placeholder; we did not contact an invoice endpoint or send a message.
Both safe templates passed three browser-parsed checks: exact visible name, exact amount and exact href. The unescaped MJML negative control produced a finance element and lost the literal <Finance> from visible text. This is an interpolation error demonstrated in our template, not a claim that MJML’s compiler is vulnerable or that React makes arbitrary input safe.
The relevant authoring difference is small:
// MJML text interpolation: escape the data first.
const escapeText = s => s.replaceAll('&', '&')
.replaceAll('<', '<').replaceAll('>', '>')
.replaceAll('"', '"');
// In a full mj-section / mj-column hierarchy:
// <mj-text>Hello ${escapeText(name)}</mj-text>
// React Email: keep the name a string child.
React.createElement(Text, null, `Hello ${name}`);
const html = await render(tree);
const plain = toPlainText(html);The compiled outputs were 5,682 bytes for our MJML template and 4,035 bytes for our React Email template. These are fixture sizes, not an efficiency ranking: our styling and component choices were not identical, and email clients were not measured. Do not choose a framework on that difference.
Choose the maintenance workflow
Choose MJML if the maintainers prefer email-specific source files and a strict compiler gate. Choose React Email if the maintainers already review React components and want the notification logic alongside application code. In both routes, put literal data preservation and the business action URL into automated checks, then review the final message in the clients your customers actually use. Browser screenshots alone cannot close that last step.
The tested core packages use MIT licenses: MJML and React Email. No hosted service, sending allowance, subscription price or enterprise support package is evaluated here. Selecting a transactional delivery service is a separate decision; so is generating the underlying invoice with document-generation software.
Methodology and limitations
Toolverly Editorial compiled both messages on 17 October 2026 in Node 26.0.0 on macOS arm64. We parsed the emitted HTML with Chrome 155.0.8059.84, checked visible strings and hrefs, generated the React plain-text alternative and executed MJML strict/soft negative controls. We retained source templates, output hashes and check results. Documentation and licenses were checked that day.
We did not send emails or test Gmail, Outlook, deliverability, screen readers, dark mode or mobile email clients. The synthetic notification is a local compiler check, not an inbox compatibility benchmark. Its name fixture covers one escaping case, not a security audit.
By Toolverly Editorial. AI assistance was used to prepare code, research and prose; the local examples were executed and their outputs reviewed before publication.
Photo by Rob Wingate on Unsplash. Read about our publication or send a correction.
