You write the email.
21 inbox clients rewrite it.
Find what breaks in Gmail, Outlook, and Apple Mail.
30 seconds to your first preview
Live Demo
The gap between your design and the inbox
Left: what you built. Right: what your users see. Switch clients to compare.
spoiler: it's Outlook
Showing 7 of 21 supported clients, covering 95%+ of email opens.
Works where you build
Lint locally. Test in CI. Let Claude and Cursor fix email rendering traps.
AI Builder
Describe the email. AI builds it, then makes it render.
Not just another generator. Emailens writes the code in your framework, then repairs its own output across 21 clients until it actually scores, catching what other AI tools ship broken.
self-heals across 21 clients in ~45 seconds
From a sentence to a shippable email
Describe it in plain English. Emailens generates React Email, MJML, Maizzle, or HTML, self-heals across every client, and you refine it in chat, then send it straight to your dashboard.
AI Fix is free to try (3 fixes). The AI Builder is a taste on Dev (3 builds/mo) and included on Pro (30/day).
How it fits
One step in the workflow you already have
Emailens doesn't replace React Email, MJML, or Maizzle. It's the check between building and shipping.
Build
Write your email in React Email, MJML, Maizzle, or raw HTML. Whatever fits your project.
Preview
Emailens checks your email against 21 clients in parallel, in your editor, CLI, or browser.
Ship
Fix issues with framework-native snippets, run CI checks, and ship emails that look right everywhere.
zero context switching · fits right into your existing CI/CD
Beyond rendering
One preview catches more than CSS bugs
Every preview also runs spam analysis, link validation, accessibility checking, image optimization, content-overflow detection, and visual-bug checks, included on all plans.
all in a single 200ms pass
Spam scoring
Heuristic content analysis: flags excessive caps, missing unsubscribe links, image-heavy layouts, CAN-SPAM address checks, and 15+ other signals.
Link validation
Catches broken hrefs, insecure HTTP links, empty mailto addresses, broken anchors, and generic "click here" anchor text.
Accessibility audit
Checks color contrast, missing alt text, heading hierarchy, lang attributes, and table semantics.
Image analysis
Flags missing dimensions, oversized files, tracking pixels without alt text, and images that break layouts.
Domain authentication
Validates SPF, DKIM, DMARC, MX, and BIMI records so your emails actually reach the inbox, not the spam folder.
Inbox preview
Analyzes subject lines and preheader text with per-client truncation limits. Detects Gmail clipping before your readers do.
Content overflow
Catches fixed-width tables and unbreakable strings that blow past the 600px email boundary and force horizontal scroll on mobile.
Visual bugs
Flags gradients with no background-color fallback and custom fonts with no web-safe stack, before Outlook renders them blank.
Outlook VML
Reads the VML inside your mso conditional comments: nested shapes that silently blank every button after them, unbalanced ghost tables, out-of-range arcsize and invalid dimensions.
Client targeting
Knows Gmail, MSO and wrap-body targeting, so scoped CSS does not tank the wrong client's score. Deprecated hacks get flagged; live ones do not count as css-hack failures.
Dark mode contrast
Re-checks every colour pair after a client inverts the email, and again below the mobile breakpoint. Contrast that passes in the light theme routinely fails in the dark one.
Design drift
Reads back the palette an email actually uses and flags near-identical colours and properties carrying more distinct values than a design system would.
Template variables
Catches unresolved merge tags: Handlebars {{var}}, Mailchimp *|TAG|*, AMPscript %%tag%%, left in text or href/src/alt attributes before they ship as raw placeholders.
Open Source
The engine is open source
The core packages that power Emailens are published on npm and open on GitHub. Use them standalone or through the web app.
@emailens/engine
The rendering compatibility engine. Parses HTML, evaluates CSS against 21 client support matrices, scores compatibility, and treats client-targeting scopes as scoped CSS rather than global failure.
@emailens/mcp
MCP server with 9 tools: analyze, preview, audit, fix, diff, deliverability, screenshots, and sharing. Works with Claude, Cursor, or any MCP-compatible AI assistant.
New
Figma plugin
Design in Figma? Preview how your email renders in 21 clients, directly inside Figma. Select a frame, click preview, get per-client scores and CSS warnings.
Works with your AI assistant
Drop Emailens into Claude Desktop, Cursor, or any MCP-compatible tool. Analyze emails, fix compatibility issues, capture screenshots, all without leaving your editor.
| or
npx -y @emailens/mcp
Pricing
Every email client, on every plan.
Starting at $9 a month.
Most email testing tools bill per client tested. Emailens doesn’t. No per-seat fees, no per-client billing, cancel anytime.
What the rendering-QA half costs elsewhere
Approximate list prices, last checked September 2026. Litmus requires annual enterprise commits; Email on Acid has migrated to Mailgun Inspect ($0.15/preview overages); Parcel prices inbox screenshots as an add-on. Read in-depth competitor comparisons →
Emailens replaces slow, expensive VM screenshot queues with an instant simulation engine tested against Can I Email and real-device benchmarks.
Two months free on Dev, two and a half on Pro when billed yearly
Free
The whole engine, 30 simulated previews a day
- 30 simulated previews per day
- All 21 email clients
- CSS compatibility report
- Dark mode preview
- 1 monitored domain · DNS check
- 7-day audit history
- 3 AI Fixes to try
- MCP server · 7 local tools
Dev
Most popularLocal developer toolkit: 100 simulated previews/day, 1 key, CLI
- 100 simulated previews per day
- Full API access · 1 key
- 3 monitored domains · SPF, DKIM, DMARC
- 30-day pre-flight audit history
- Share links & Visual Diff
- HTML size & 102KB clipping checks
- MCP screenshots + sharing
- AI Fix · 10/mo + Builder · 3 builds/mo
Pro
RecommendedProduction gate & CI/CD: zero broken emails deployed
- Pre-send gate · spam heuristics & regressions
- CI/CD integration & GitHub Action
- 10 monitored domains · drift alerts
- 1-year audit history & compliance archive
- Unlimited simulated previews · all 21 clients
- Full API access · 10 keys
- AI Fix + AI Builder · 30 builds/day
- MCP unlimited screenshots
- Everything in Dev
Not the same product. Litmus and Mailgun Inspect bundle marketing analytics and delivery infrastructure with per-preview limits; Parcel is an in-browser code editor. Emailens delivers developer-first rendering QA across 21 clients via CLI, CI/CD, and MCP without campaign tracking bloat.
Cancel anytime. Upgrade or downgrade in one click.
no hidden limits · 30-day money-back guarantee
Team plan
Not built yet. If your team needs seats, a shared workspace and unlimited API and CI/CD, tell us what that looks like and we’ll size it with you.
Talk to usDaily game
Think you know what Outlook breaks?
Renderle deals five CSS features a day. Call whether each one renders in Gmail, Outlook, Apple Mail, Yahoo and Samsung Mail, then share the grid. Built on the same support data the linter runs on, so a wrong guess is a rendering trap you now know about.