Email on Acid is an email pre-send testing platform that previews how your emails render across 100+ clients and devices. Strengths: comprehensive rendering previews, spam filter testing, accessibility checks, link validation, lower cost than Litmus. Weaknesses: no analytics or tracking, testing-only tool, UI could be more intuitive. Best for email marketers and developers who need rendering QA before hitting send — especially those who find Litmus too expensive.
Email on Acid Review 2026: Email Testing and Rendering Previews
What Email on Acid Does
Email on Acid is a pre-send testing platform. You paste your HTML or send a test email, and it shows you screenshots of how that email renders across 100+ email clients — desktop Outlook (every version), Gmail (web, iOS, Android), Apple Mail, Yahoo, and dozens more.
Beyond rendering, it checks your email against spam filters, validates all links, tests image blocking behavior, and runs accessibility audits. It's a QA tool for email, not a sending platform.
Pricing (2026)
| Plan | Price | Users | Key Features |
|---|---|---|---|
| Basic | $74/mo | 1 | Unlimited tests, 100+ clients, spam testing |
| Premium | $134/mo | 3 | + Accessibility checks, advanced analytics, API |
| Enterprise | Custom | Unlimited | + SSO, dedicated support, custom integrations |
Sinch (which also owns Mailgun and Mailjet) acquired Email on Acid in 2021. Pricing has been relatively stable since.
Strengths
Comprehensive rendering. 100+ email clients and devices, including notoriously difficult ones like Outlook 2016/2019 (Word rendering engine), Gmail with images disabled, and dark mode variants. This is the core value and it delivers.
Spam testing. Built-in spam filter testing checks your content against major filters. Not as deep as GlockApps for inbox placement, but useful as a pre-send content check.
Accessibility. The Premium plan includes accessibility checking — color contrast, alt text validation, semantic structure, and screen reader compatibility. Increasingly important as accessibility regulations expand.
Link validation. Checks every link in your email for broken URLs, redirect chains, and blacklisted domains. Catches embarrassing errors before they reach inboxes.
Practitioner note: The dark mode previews alone justify the subscription for many teams. Dark mode rendering is unpredictable across clients — an email that looks perfect in Gmail light mode can be unreadable in Outlook dark mode. Testing before sending prevents support tickets.
Weaknesses
Testing only. Email on Acid doesn't send emails, doesn't track analytics, and doesn't help with strategy. It's purely QA. If you need an all-in-one platform, Litmus does more (at a higher price).
UI is functional, not elegant. The interface gets the job done but doesn't feel modern. Navigating between tests, comparing client renders, and sharing results with teammates could be smoother.
No inbox placement testing. The spam check analyzes your content against filter rules, but it doesn't send to real inboxes and report placement like GlockApps does. Different type of testing with different value.
Sinch ecosystem uncertainty. Sinch owns Mailgun, Mailjet, and Email on Acid. There's always a risk of product consolidation or strategic neglect. So far the product has been maintained.
Practitioner note: I use Email on Acid for rendering QA and GlockApps for placement testing. They answer different questions — "does my email look right?" versus "does my email reach the inbox?" You need both if deliverability matters.
Who Should Use Email on Acid
Good fit:
- Email developers building custom HTML templates
- Marketing teams sending to diverse audiences (Outlook desktop users)
- Agencies managing email design for multiple clients
- Anyone who's been burned by Outlook rendering issues
Bad fit:
- Teams that only send plain-text emails
- Senders who need inbox placement testing (use GlockApps)
- Small senders using template-based ESPs (your ESP handles rendering)
The Bottom Line
Email on Acid is the affordable alternative to Litmus for email rendering QA. If you build custom HTML emails and send to audiences that include Outlook desktop users, you need a rendering preview tool. Email on Acid does this well at roughly half the cost of Litmus. If you need analytics, collaboration, and an email builder on top of testing, pay up for Litmus.
If your emails look fine in testing but still aren't reaching inboxes, the problem isn't rendering — it's deliverability. Schedule a consultation and I'll diagnose what's actually going wrong.
Sources
- Email on Acid: Pricing
- Email on Acid: Email Client Preview List
- Sinch: Email on Acid Acquisition
v1.0 · March 2026
Frequently Asked Questions
What does Email on Acid do?
Email on Acid tests your email before you send it. It shows rendering previews across 100+ email clients (Gmail, Outlook, Apple Mail, mobile), runs spam filter checks, validates links, checks image blocking behavior, and tests accessibility compliance.
How much does Email on Acid cost?
Basic plan starts at $74/month for 1 user with unlimited testing. Premium is $134/month with advanced features and 3 users. Enterprise pricing is custom. Sinch acquired Email on Acid in 2021, and pricing has shifted since.
Is Email on Acid better than Litmus?
Email on Acid is cheaper and covers rendering previews well. Litmus offers more features beyond testing — analytics, collaboration tools, email builder. If you only need pre-send testing and rendering QA, Email on Acid gives you comparable results at a lower price.
Want this handled for you?
Free 30-minute strategy call. Walk away with a plan either way.