For years, anyone who sent serious email had the same two tools bookmarked: Litmus and Email on Acid. They were the rendering-preview workhorses — paste in your HTML, see how it looks in Outlook 2016, dark-mode Gmail, and Apple Mail before you hit send. In 2026, both of them changed in ways that quietly reshape the entire email-testing market. One got dramatically more expensive. The other is being folded into a different product entirely.
If you build or QA email for a living, the affordable middle of this market has effectively disappeared. Here's what happened and what your options are now.
Litmus moved upmarket — hard
Litmus has long been the premium choice, but it used to have an on-ramp. Its Basic plan sat around $99/month and Plus around $199/month — pricey, but reachable for a freelancer or a small in-house team that cared about rendering quality.
That on-ramp is gone. Litmus eliminated its cheaper tiers in 2025, and the entry point is now the Core plan starting at roughly $500/month. That's not a tweak; it's a repositioning. Litmus is telling small senders, politely, that they are no longer the target customer. The product is now aimed squarely at enterprise marketing teams and agencies who run high-volume campaigns where a single rendering bug can cost real revenue — and who can justify five figures a year on email QA.
For those teams, Litmus is still excellent: previews across 100+ clients, spam-filter testing across ISPs, analytics that go well beyond open rates, and collaborative approval workflows. But if you were paying $99/month and loved it, your renewal is about to look very different.
Email on Acid is becoming Mailgun Inspect
The other half of the duopoly took a different exit. Email on Acid was acquired by Sinch — the communications platform that also owns Mailgun and Mailjet — and is now being folded into a new product called Mailgun Inspect. Existing-customer migration begins in 2026.
On paper, consolidation like this can be good news: more engineering resources, tighter integration with a sending platform, a single bill. In practice, product absorptions are always a little nerve-racking for the people who depend on the original tool. URLs change, feature parity is never guaranteed on day one, and workflows you've built around the old dashboard have to be relearned. Email on Acid's entry pricing sat around $99/month, and where that lands inside Mailgun Inspect is the open question every current customer is asking.
If you're on Email on Acid today, the practical advice is simple: read the migration notices carefully, export anything you need (saved tests, templates, historical results), and confirm that the specific clients and checks you rely on survive the transition before you commit your team's workflow to the new product.
What this means if you test email
The headline is that the two dedicated, best-in-class email-testing tools are now either much more expensive or in the middle of a platform migration. The comfortable, affordable middle tier — the $99–$199/month sweet spot — has thinned out considerably.
A few practical takeaways:
- **Small senders and freelancers** should reassess before auto-renewing. The jump to $500/month for Litmus is hard to justify if you send a handful of campaigns a month. Lighter-weight preview tools and your email platform's built-in test-send features may cover 80% of your needs.
- **Developers** building transactional email should note that deliverability and rendering are increasingly bundled into sending platforms themselves. If you already send through a major API provider, check what inbox-preview and validation features ship in the box before paying for a standalone tool.
- **Enterprise teams** largely keep their tools — Litmus's repricing is aimed at you, and you were probably already paying near that range. The bigger watch item is the Email on Acid migration if that's your stack.
- **Everyone** should remember that the foundation of deliverability isn't a preview tool at all — it's authentication (SPF, DKIM, DMARC), list hygiene, and consistent engagement. A perfect render that lands in spam is still worthless.
The bottom line
The email-testing market just consolidated and moved upmarket in the same year. Litmus is now a premium-only product, and Email on Acid is mid-transition into Mailgun Inspect. Neither tool is gone — but the era of cheap, dedicated, set-and-forget email previewing is fading. Audit what you actually use before your next renewal, and don't pay enterprise prices for a feature your sending platform may already include.