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Test on 3 clients.
Cover 86% of opens.

Apple Mail. Gmail. Outlook. AI-powered analysis. From $29/mo.

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Test Your Email in 30 Seconds

Enter your FROM address below, then send your email to our preview address.

How it works

01

Send to your inbox

Forward your email to your unique RenderStack address. That's it.

02

We render it everywhere

Apple Mail, Gmail, Outlook—light and dark mode. Desktop and mobile.

03

Get AI insights instantly

302+ compatibility checks flag issues. Plain English explanations. Code fixes.

Litmus tests 100+ email clients.

You need three.

52%Apple Mail
+
27%Gmail
+
7%Outlook
=
86%coverage

Same coverage. Fraction of the cost.

$500/moLitmus Plus
$74/moEmail on Acid
From $29/mo

RenderStack — no enterprise tax

Everything you need

Send-to-test

No HTML pasting. Forward and go.

Desktop + mobile

Both viewports, every client.

Dark mode

Automatic previews, no extra work.

AI analysis

302+ checks flag rendering issues.

Fast

Results in under 60 seconds.

Free tier

AI linting, no credit card required. Try it free →

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