Emailens vs Email on Acid
Legacy SaaS pre-deployment screenshot checklist vs modern developer QA pipeline. An honest, technical comparison of features, rendering architecture, developer workflow, and total cost of ownership.
Email on Acid Is Sunsetting: What the Mailgun Inspect Transition Means for You
Following Sinch's acquisition of Email on Acid, the standalone platform is officially being sunset and rolled into 'Mailgun Inspect'. Accounts renewing throughout 2025 and 2026 are being transitioned onto new terms, with users reporting significant changes to pricing and preview quotas.
- • Unlimited Previews Removed: Legacy 'unlimited previews' plans are discontinued in favor of capped monthly quotas and $0.15 per preview overage charges.
- • Price Increases: Users report monthly costs jumping from ~$74/mo up to $99+/mo, with annual payment lock-in.
- • Bundling with Sending Infrastructure: Email QA is now positioned as an add-on to Mailgun/Sinch email delivery rather than an independent testing tool.
- • Workflow Disruptions: Classic features like Campaign Precheck have been modified or absorbed into delivery metrics dashboards.
Emailens provides an independent, open-source email QA alternative with flat predictable pricing ($9 to $19/mo), unlimited team usage, no overage penalties, and zero vendor lock-in.
Start Free MigrationEmail on Acid was designed in the 2010s as a manual browser checklist for email marketing specialists before sending newsletters. Emailens is an automated testing platform engineered for developers building transactional and product emails with React Email, MJML, and Tailwind in modern git workflows.
Choose Emailens if:
- • You want rendering QA integrated into pull requests via GitHub Actions
- • You write emails using React Email, MJML, or Maizzle rather than raw HTML
- • You want instant AST CSS compatibility scoring rather than waiting for screenshot queues
- • You develop with AI coding assistants (Cursor, Windsurf, Claude) and want MCP integration
- • You want predictable monthly pricing ($9–$19) without $0.15/preview overage penalties
Choose Email on Acid if:
- • You already use Sinch / Mailgun for sending and want bundled Mailgun Inspect billing
- • Your workflow is strictly browser-based manual checklist verification before campaigns
- • You need legacy email client configurations dating back to Windows XP / Outlook 2003
Under the Hood: Architecture & Mechanics
How Emailens differs technically from legacy screenshot queue services.
Detailed Feature Matrix
Side-by-side comparison across rendering QA, developer integration, and collaboration.
Rendering & Code QA
| Capability | Emailens | Email on Acid |
|---|---|---|
| Email rendering previews | 21 core inbox engines on every test | 100+ client/device combinations |
| CSS AST compatibility analysis | | Basic HTML linting |
| Dark mode simulation & color inversions | | |
| Spam filter & blocklist testing | | |
| Accessibility validation (WCAG) | | |
| Link and image validation | | |
| Campaign Precheck workflow | Automated in CLI/CI | Manual web checklist |
Developer Experience & Automation
| Capability | Emailens | Email on Acid |
|---|---|---|
| Open-source engine | | |
| GitHub Action CI/CD gate | | |
| CLI tool for terminal testing | | |
| Model Context Protocol (MCP) server | | |
| React Email & Tailwind JSX support | | |
| MJML & Maizzle compilation | | |
| Actionable code fixes for Outlook/Gmail | | |
| REST API | Included on $9/mo plan | Included on Premium tiers |
Pricing & Team Terms
| Capability | Emailens | Email on Acid |
|---|---|---|
| Entry price | $0 (Free tier) or $9/mo | $74/mo (billed annually: $888/yr) |
| Overage billing charges | None (never surprise billed) | ~$0.15 per preview over allotment |
| Seat limits | No seat fees | 1 user (Basics) / 3 users (Premium) |
Pricing & Total Cost of Ownership
Transparent pricing without hidden seat fees or overage surprises.
Emailens
Flexible Monthly / AnnualEmail on Acid
Published TiersWhy Engineering Teams Choose Emailens
Four fundamental differences in developer workflow and engineering philosophy.
8x lower cost with zero annual lock-in
Email on Acid requires annual commitments starting at $888/year and charges overage fees if you test frequently. Emailens starts at $9/month with month-to-month flexibility and no surprise fees.
Test where you code, not in a browser tab
Stop copying and pasting raw HTML into a web form every time you tweak padding. Run Emailens directly from your terminal or let our GitHub Action check every git commit automatically.
Framework-native fixes for modern stacks
Email on Acid only analyzes compiled HTML. Emailens understands React Email JSX and MJML, providing code fixes written in the component syntax your team actually authors.
Independent & developer-focused
Following its acquisition by Sinch and absorption into Mailgun Inspect, Email on Acid's roadmap is geared toward enterprise marketing bundles. Emailens is 100% focused on developer email engineering.
Frequently Asked Questions
What is happening to Email on Acid with Mailgun Inspect?
Sinch (owner of Mailgun) has begun migrating Email on Acid customers to 'Mailgun Inspect', consolidating pre-send testing with email delivery services. If you only want clean, fast rendering QA without switching your email sending provider, Emailens provides an independent, open-source alternative.
Can Emailens check dark mode rendering like Email on Acid?
Yes. Emailens accurately simulates client-specific dark mode behavior, including Outlook's aggressive background inversion, Gmail's partial color mapping, and Apple Mail's CSS color-scheme compliance.
How does Emailens' speed compare to Email on Acid?
Email on Acid typically takes 2 to 4 minutes to generate a full set of client screenshots. Emailens provides an instant CSS compatibility verdict in under 50ms using our local AST engine, followed by parallel headless screenshot rendering that completes in seconds.
Switch from Email on Acid in Minutes
Start with 30 free daily previews across all 21 clients. No credit card required, no sales call, and zero seat limits.