01 / Paste
Paste or upload the HTML
Drop in a build with a subject line. Nothing to install.
01 · Email QA
Unlimited email previews.
Built for humans and agents.
See exactly how your email renders across the clients that matter — light and dark — without counting previews. Paste HTML, forward a message, or call the API.
28 emulated client profiles · REST API + MCP server · invite-only beta
test #4812 · summer-sale.html3 / 16 done
Gmail
done
Outlook.com
done
Yahoo Mail
done
AOL Mail
queued
GMX
queued
Outlook 365
queued
02 · Why now
Email on Acid became a metered bill.
Inspect Basic
$99
1,000 previews included
Every preview after
$0.15
per client · per mode
One honest test
~100
50 clients × light + dark
Runs before the meter
10
then it starts charging
Email on Acid was acquired by Mailgun (Sinch) and folded into Mailgun Inspect. Testing that used to be unlimited now has a counter on it. That is the day we started building EmailOnSteroids. Read the full story
03 · How it works
Three ways in. One pipeline. Every client back.
02 / Forward
Send it to your inbox address
Mail sent to your account address creates a test automatically.
03 / API
POST it from your pipeline
The same endpoint your CI job — or your agent — already calls.
04 · Coverage
The clients your audience actually opens in
Gmaillight · dark
Outlook.comlight · dark
Yahoo Maillight · dark
AOL Maillight
GMXlight
Outlook 365light · dark
Outlook 2019light
Apple Maillight · dark
Thunderbirdlight · dark
Windows Maillight · dark
iOS Mail 18light · dark
iOS Mail 17light · dark
Gmail Androidlight · dark
Gmail iOSlight · dark
Outlook Androidlight · dark
Samsung Maillight
Gmail (non-Google address)light
Proton Maillight
Gmail (narrow window)light
Outlook.com (macOS)light
Outlook 2013light
Outlook for Maclight · dark
Outlook 365 (narrow pane)light
Apple Mail (narrow)light
Apple Mail (iPad)light · dark
Yahoo Mail (Android)light
iOS Mail 18 (iPhone SE)light
Gmail Android (folded)light
05 · What you get
Everything the QA loop needs — nothing metered
01
The grid fills as renders finish
Clients return at wildly different speeds, so results stream in per client rather than making you wait for the slowest one.
02
Share links that expire
Unguessable slug, no-index, a time-to-live you pick at creation, and a hard delete when it lapses.
03
An MCP server, not just an API
Your agent can create a test, read each client's status, retrieve previews, and iterate on markup without a human in the loop.
04
Re-run and compare
Every run is kept, so you can prove a fix actually landed instead of trusting that it did.
06 · Pricing
Flat. Unlimited. No preview counter.
Monthly · EUR · final price, no VAT
Free
€0 /month
1 member
- 5 tests per UTC month
- 3 representative client profiles — Gmail, Outlook 365, iOS Mail 18
- Latest 5 tests retained
- REST API + MCP server
- No share links
- No spam, link or image analysis
- No code compatibility analysis
- Low render priority
Plus
€39 /month
1 member
- Unlimited tests
- All 28 emulated client profiles
- Latest 25 tests retained
- REST API + MCP server
- Share links
- Spam, link and image analysis
- No code compatibility analysis
- Medium render priority
ProBeta invites start here
€69 /month
1 member
- Unlimited tests
- All 28 emulated client profiles
- 90 days of history
- REST API + MCP server
- Share links
- Spam, link and image analysis
- Code compatibility analysis
- High render priority
07 · Our story
We didn't set out to compete. We set out to keep testing.
“A tool we used every day turned into a meter. So we rebuilt the part we actually needed.”
Read the full storyThe setup
Email on Acid was a daily email-QA tool for a lot of teams.
The acquisition
Sinch / Mailgun acquired it and folded it into Inspect.
The change
Unlimited testing became 1,000 previews, then $0.15 each.
Today
EmailOnSteroids: flat pricing and an API-first QA loop.
08 · Early access
We're opening it invite by invite.
A small group gets a product that works. Every early invite starts on Pro.