Email on Acid Pricing in 2026: Plans, Limits, and What Changed

Email on Acid pricing has gotten confusing over the past year, and not because the product got more complicated. It's because the product is disappearing.

If you've gone looking for a current Email on Acid pricing page recently, you've probably landed on Mailgun Inspect instead. That's not a mistake or a broken redirect. Sinch, which owns both Email on Acid and Mailgun, is folding Email on Acid's rendering and pre-send testing into Mailgun Inspect, and the pricing you see now reflects that consolidation.

This matters for two groups of people. If you're an existing Email on Acid subscriber (sometimes typed as "emailonacid" or "emails on acid" in search), you need to know what changes, what doesn't transfer, and what your renewal is actually going to cost. If you're evaluating email testing tools for the first time, you need current numbers, not the legacy pricing that's still floating around third-party directories and comparison posts.

We'll walk through what Mailgun Inspect costs today, where the plan limits tend to bite in practice, what alternatives are worth a look, and where rendering QA stops and deliverability monitoring starts. Those are two different purchases, even though they get lumped into the same line item on a lot of marketing budgets.

Email on Acid pricing at a glance

Here's what Mailgun Inspect currently charges, based on the official pricing page.

Alt text: Email on Acid / Mailgun Inspect pricing tiers table. Caption: Current Mailgun Inspect pricing as of publish date. Pricing verified November 2025. Check the official Mailgun Inspect pricing page before budgeting, since Sinch has adjusted tiers before and the migration period may bring further changes.

A few things worth flagging before you compare this to what you remember paying.

Older posts and third-party software directories still list "acid email" pricing at figures like $74/mo (billed annually) or tiered plans at $99/$179/$599/mo. Those numbers are legacy pricing, reported by third-party directories between roughly 2023 and early 2025, before the Mailgun Inspect transition. They are not what you'll be charged today. If a page quoting those numbers doesn't carry a clear date, treat it as outdated.

The overage rate is the number most teams underweight during evaluation. At $0.15 per preview beyond your allowance, a team that regularly runs 1,400 previews a month on a Basic plan isn't paying $99. They're paying $99 plus $60 in overage, every month, as a predictable recurring cost rather than an occasional spike.

Why you're seeing Mailgun Inspect instead of Email on Acid

Sinch acquired Email on Acid years ago alongside other deliverability and testing assets, and has been gradually merging the Email on Acid brand into Mailgun's broader product suite. Mailgun Inspect is the result: one testing product that absorbs Email on Acid's rendering and pre-send checks instead of running them as a separate, standalone tool.

The migration timeline is public but not yet fully executed. Sinch has stated migration begins June 2026, and has promised a discount for customers transitioning from legacy Email on Acid plans, though that discount hasn't been quantified anywhere official. We cover what else is confirmed, including what happens to your existing test history, in the "What changes for existing Email on Acid customers" section below.

For teams currently budgeting renewal costs, this is also the point to ask a broader question: is rendering QA the only testing gap in your stack, or is it one piece of a bigger problem? We cover that distinction later in this piece.

What's included in each plan — and where the limits bite

Mailgun Inspect's two tiers look similar on paper. The real differences show up once you map them against how your team actually works.

Alt text: Feature comparison table for Mailgun Inspect plans. Caption: Where the limits actually bite.

Details like API access, team seat counts, and support tier aren't published with specificity on the current pricing page, and they can vary by account setup. If those details matter to your decision, confirm them directly with Sinch's sales team before signing an annual contract rather than relying on a comparison chart to settle it.

Where the limits bite in practice

The client/device coverage number is the same across both tiers: 100+ clients and devices. You're not paying more for broader rendering coverage between Basic and Premium. You're paying for more previews against that same coverage.

That distinction matters for how you budget. A team running one template through 15 client/device combinations before every send uses 15 previews per test. At that rate, 1,000 previews on Basic covers roughly 66 full test runs a month. For a team sending two or three campaigns a week, each needing a pre-send check, that math gets tight fast, especially once you add subject line variants, mobile-specific checks, or re-tests after a fix.

Agencies feel this first. If you're running rendering QA across 10 client accounts, and each client gets a full test pass before every send, you can burn through a 1,000-preview allowance in a few weeks without anyone treating that as unusual. The Premium tier doubles the allowance, not the coverage, so the jump from $99 to $199 buys you headroom rather than new capability.

Preview-based billing is standard for rendering QA tools, and Mailgun Inspect's model is straightforward once you know where to look. The risk is in assuming the plan tier you need maps to the features you want, when it actually maps to volume.

How to estimate your real monthly cost before you commit

The sticker price on Mailgun Inspect's pricing page is rarely the number you'll actually pay if you send regularly. Here's a simple way to estimate it before you sign an annual contract.

Step 1: Count your test runs, not your campaigns.

A "test run" is one full pass through your client/device matrix for a single email. If you test 20 clients and devices per campaign, that's 20 previews, not 1. Pull your last three months of campaign volume and multiply by your typical test depth.

Step 2: Add re-tests.

Almost no team gets a template right on the first pass. If you catch a rendering bug in Outlook and need to re-run the test after a fix, that's a second full test run against the same campaign. Teams that iterate on templates, which is most teams, should budget for at least one re-test per campaign, sometimes more during a redesign.

Step 3: Multiply by your client/device depth, not just your send count.

This is the step that trips people up. If you send 15 campaigns a month but test each one against 25 clients and devices, your preview usage is 375 for that month, not 15. Scale that against the 1,000-preview Basic allowance and you can see how quickly agencies and high-cadence senders cross into overage.

Step 4: Price the overage honestly.

At $0.15/preview, overage isn't punitive on its own. But it compounds. A team running 1,500 previews a month on Basic isn't paying $99. They're paying $99 plus $75 in overage, every month, as a predictable line item rather than an occasional surprise. If that's your actual usage pattern, Premium's $199/mo for 2,000 previews is very likely the cheaper plan in practice, even though it looks like a bigger sticker price upfront.

Run this math with your own numbers before you commit to an annual term. Preview-based pricing rewards teams that know their real test volume and penalizes teams that guess.

How to compare email testing costs beyond preview limits

Preview allowance and overage rate are the easiest numbers to compare across vendors, but they're not the only cost that matters when you're building a testing budget.

A few things worth pricing out before you lock in a plan:

What's actually covered in the base price. Rendering QA tools like Mailgun Inspect bundle pre-send content checks into the same subscription as preview rendering. Deliverability monitoring tools are usually priced separately, often by sending volume or monitored domains rather than by preview count. If your current budget line is labeled "email testing" and only covers one category, you may be underbudgeting for the other.

What happens when you exceed a limit. Overage pricing varies by vendor, and some tools cap usage hard rather than billing overages, which can mean a blocked test mid-campaign. Know which model you're signing up for.

What you lose if you switch providers. As the Email on Acid migration shows, test history and saved configurations don't always transfer between platforms, even within the same parent company. Factor migration risk into total cost of ownership, not just the monthly rate.

Whether you're paying for QA, monitoring, or both. This is the most common budgeting gap we see. Teams price out rendering QA tools against each other, settle on one, and assume deliverability visibility is covered somewhere in that spend. It usually isn't. If you want to see what a monitoring layer costs separately from preview-based QA, you can compare Mailora plans and pricing against your current rendering QA spend.

What changes for existing Email on Acid customers

If you're already an Email on Acid subscriber, the pricing conversation above is secondary to a more immediate question: what happens to your account when migration starts.

A few things are confirmed, and worth treating as settled rather than speculative:

Migration begins June 2026. This is a timeline, not a single cutover date. Expect a transition window rather than an overnight switch, though Sinch hasn't published granular detail on how phased the rollout will be.

Existing previews and test history do not transfer. This is stated plainly because it deserves no hedging. If your team has built a library of historical render comparisons, saved test configurations, or client-facing reports inside Email on Acid, none of that carries over automatically into Mailgun Inspect. If you need that history for compliance, client reporting, or internal reference, export or archive it before your account transitions.

A migration discount has been promised, not quantified. Sinch has stated that customers moving from legacy Email on Acid plans will receive some form of discount during the transition. No percentage or dollar figure has been published officially as of this writing. Treat any specific number circulating online as unverified until it appears on Sinch's own pricing or migration documentation.

Your renewal pricing will likely shift to current Mailgun Inspect rates. If you're on a legacy plan at $74/mo or one of the older tiered structures, expect your next renewal to reflect Basic or Premium pricing, not your historical rate, unless the migration discount specifically addresses that gap.

Practically, this means existing customers should do three things before their renewal date: export anything from their test history they want to keep, estimate their real preview usage using the method above, and confirm directly with Sinch, not a third-party directory, what their specific account's migration terms look like. Account-level migration details can vary, and the only reliable source is Sinch's own communication to your account.

Email QA vs. email deliverability monitoring: two different purchases

It helps to separate what you're actually buying when you sign up for Mailgun Inspect, GlockApps, or Mailora. These tools get grouped together under "email testing" in buyer research, but they answer different questions.

Mailgun Inspect (and Email on Acid before it) is a rendering QA tool. You upload or send a test email, it renders across 100+ clients and devices, and you see how your layout, images, and dark mode behavior hold up in Outlook versus Gmail versus Apple Mail. It also runs pre-send content checks, a heuristic scan of your HTML and copy for things that commonly trigger spam filters. That's valuable, and it's a different job than what Mailora does.

Mailora is a deliverability monitoring platform. It doesn't render your email in 100 clients. Instead, it tracks where your messages actually land across ISPs through inbox placement testing, monitors domain and IP reputation over time, checks your sending domains against major email blocklists, and gives visibility into SPF, DKIM, and DMARC authentication health. The question Mailora is built to answer isn't "does this look right." It's "did this reach the inbox, and if not, why."

Those are both legitimate pre-send and post-send questions. They're just not the same question, and no single tool currently answers both well. If your team wants to validate layout and catch a broken template before a send, and separately wants to know whether your last three campaigns landed in Gmail's Promotions tab or actual spam, you're looking at two different categories of tool, not one tool with two modes.

If you haven't separated these in your budgeting, it's worth doing that before you commit to a Premium-tier annual contract assuming it covers your deliverability visibility too. It doesn't, and it was never built to. If you want to see where your last few sends actually landed, you can test email deliverability before you send as a separate check alongside your rendering QA process.

What a preview allowance can't tell you about sending health

A pre-send content check inside Mailgun Inspect will flag spam-trigger language, broken links, missing alt text, and HTML issues that commonly correlate with poor filtering outcomes. That's useful information. It is not a measurement of what actually happened when your email hit a real inbox.

This gap matters more than it might seem at first glance. A spam score or content heuristic is a prediction based on patterns. It tells you an email resembles messages that historically perform poorly. It does not tell you that your email, from your domain, with your current sender reputation, landed in spam for a meaningful percentage of recipients this week.

A team can pass every pre-send content check, ship a clean template with no HTML errors, and still see placement degrade because their sending domain picked up a reputation issue, their DMARC alignment drifted after someone added a new ESP, or a subset of their list started marking messages as spam. None of that shows up in a rendering tool's pre-send scan, because none of it is a property of the email itself. It's a property of how that email interacts with your sending history and ISP trust signals over time.

DMARC reporting is a useful related example. If you have DMARC monitoring in place, aggregate reports show you alignment data and which sources are sending on your domain's behalf, including sources you didn't authorize. That's genuinely useful for catching spoofing and unauthorized senders. But DMARC reports don't show inbox versus spam placement. They show authentication outcomes, not filtering outcomes. A message can pass DMARC perfectly and still land in spam, because DMARC answers "is this really you" and inbox filtering answers a separate question about trust, engagement, and content signals.

Pre-send checks and DMARC monitoring are both still worth having. Each covers one piece of a larger picture, and no tool, including Mailora, can promise inbox placement as a guaranteed outcome. Placement depends on sender reputation, recipient engagement, list health, and ISP-specific filtering logic that shifts over time. What continuous monitoring can do is show you the pattern early enough to act on it, rather than finding out from a revenue report three weeks later.

Email on Acid and Mailgun Inspect alternatives worth comparing

If you're evaluating Mailgun Inspect's pricing and considering whether a different tool fits your workflow better, it's worth knowing the landscape splits into two categories: rendering QA tools and deliverability-focused tools. Mixing these up during evaluation is where most budgeting mistakes happen.

Rendering and pre-send QA alternatives include Litmus, which overlaps closely with what Mailgun Inspect does: client/device rendering previews and pre-send content checks. If your core pain point is template bugs, Litmus is the most direct comparison point. Mail-Tester is a lighter-weight, free-adjacent option for a quick spam-score style check on a single email, useful as a spot-check rather than a full QA workflow.

Deliverability and reputation-focused alternatives include GlockApps, which offers inbox placement testing and spam filter testing across providers, positioned closer to what deliverability teams need than to rendering QA. MxToolbox provides DNS, blocklist, and authentication record lookups, useful for diagnosing specific technical issues. Validity Everest focuses on sender reputation and inbox placement monitoring at an enterprise scale. ZeroBounce is primarily a list validation and hygiene tool, which indirectly supports deliverability by reducing bounce and complaint risk. On the lighter end, MailGenius and InboxMonster offer scaled-down spam testing and monitoring aimed at smaller teams.

None of these tools, including Mailora, do everything. If you're specifically weighing Email on Acid pricing against a deliverability-first approach, it's worth reading a closer breakdown of Email on Acid alternatives for deliverability-focused teams before you commit budget to either category.

Matching the tool to the question you're actually asking

The clearest way to decide what you need is to work backward from the specific question you're trying to answer before a send, or after one.

Alt text: Decision framework showing email QA versus deliverability monitoring. Caption: Match the tool to the question you're actually asking.

Choose the right tool for the question you need answered

Use this as a short checklist before you renew or switch:

• If your last three complaints from stakeholders were about broken layouts, missing images, or dark mode issues, rendering QA is the right spend. Mailgun Inspect's preview-based pricing is a reasonable way to pay for that.
• If your last three complaints were about open rates dropping, a client asking why their campaign underperformed, or a surprise blocklisting, that's a monitoring gap, not a rendering gap.
• If you can't currently answer "where did our last campaign actually land" without guessing, that's the clearest sign you're missing the monitoring layer, regardless of how good your rendering QA tool is.
• If you're an agency managing multiple client sending domains, you likely need both categories running in parallel, since rendering issues and reputation issues surface independently of each other.

Many teams, especially agencies and mid-to-high volume senders, end up needing both. That's two layers of QA covering two different failure modes, not redundant spend. You can review Mailora's deliverability monitoring features to see how the monitoring side maps against what your rendering QA tool currently leaves uncovered.

Conclusion

Email on Acid pricing isn't static anymore, and the Mailgun Inspect migration means the numbers you find on older review sites or forum threads probably aren't the ones you'll pay. Basic and Premium plans, preview-based limits, and per-overage charges are the current reality, and if you're an existing customer, your old tests and previews won't carry over automatically.

Budgeting for this correctly means separating two different line items: what you spend on rendering QA to catch template and layout issues before you send, and what you spend on deliverability monitoring to know whether your email actually reached the inbox. Mailgun Inspect covers the first. It was never built to cover the second, and neither was Email on Acid before it.

If your team has rendering QA handled but still can't answer basic questions about placement, reputation, or DMARC alignment, that gap is worth closing separately. Visit usemailora.com to see what's currently happening with your sending domains before you lock in next year's testing budget, or go ahead and run your first test directly.

FAQs

How much does Email on Acid cost in 2026?

Email on Acid, sometimes searched as "emailonacid" or "email on acid pricing," is now sold as Mailgun Inspect. As of publish, Basic is $99/month with 1,000 previews, and Premium is $199/month with 2,000 previews. Overage previews beyond your plan limit are billed at $0.15 each.

Is Email on Acid the same as Mailgun Inspect?

Yes. Mailgun Inspect is the current product name following Email on Acid's integration into the Mailgun brand. Functionally it's the same rendering QA tool, now sold under new pricing and plan names, with migration for existing customers beginning June 2026.

What happens to my existing Email on Acid tests and previews after migration?

They do not transfer. Existing previews, test history, and saved checks stay on the legacy system and won't carry over into your new Mailgun Inspect account. A migration discount has been mentioned but no specific amount has been published, so budget as if you're starting fresh.

What counts as a "preview" against my monthly allowance?

Each time you render a single test email across your selected clients and devices, that counts as one preview against your plan's limit. High-volume QA teams testing frequently across many client combinations can burn through 1,000 or 2,000 previews faster than expected, especially during heavy campaign-launch months.

Does Email on Acid or Mailgun Inspect show inbox placement and deliverability data?

No. It runs pre-send content checks, which are heuristic scans for spam-trigger patterns, not a measurement of where your email actually landed. For inbox placement, reputation tracking, and DMARC signal analysis, you need a dedicated deliverability monitoring tool.