Virtual previews

Virtual previews render your email through 13 different device profiles — iPhones, iPads, Android phones, Android tablets — and produce a screenshot of each. It's the fastest way to verify your template doesn't break on a 320 px iPhone SE or a landscape iPad before a campaign goes out.

What it is — and isn't

Virtual previews use a real browser (Chromium) with each device's actual user-agent, pixel density, and viewport dimensions. What you see is what Chromium would render at that viewport.

This is not real-email-client rendering. Gmail strips CSS differently than Chromium does. Outlook desktop uses Microsoft Word's rendering engine — not a browser at all. Apple Mail has its own quirks. Virtual previews catch layout problems (text wrapping wrong on small screens, columns stacking awkwardly on tablets, fixed widths overflowing) — they don't catch client problems (Gmail removing your background image, Outlook stretching your buttons).

For real-client testing, send yourself a real test via Send Test in the editor and open it in your actual Gmail, Outlook, and Apple Mail accounts.

Generating a preview

1. Open the email in the editor.
2. From the email's actions menu, click Generate Preview.
3. A new preview is queued. Status is PENDING while the job runs.

Generation typically takes about a minute for non-admin accounts (the job runs on a 1-minute delay to batch). The preview's status flips to COMPLETE when all 13 screenshots are ready.

Device list

The renderer iterates through all 13 profiles for every preview — you don't pick which ones:

Category	Devices
iPhones	iPhone 15 Pro Max (large, 430×739), iPhone 15 Pro (regular, 393×659), iPhone SE (small, 320×568)
iPads	iPad Pro 11 (portrait & landscape), iPad Mini (portrait & landscape)
Android phones	Galaxy S9+, Galaxy S8, Pixel 5
Android tablets	Galaxy Tab S4 (portrait & landscape)

The three iPhone sizes are deliberately spread across the size range — if your email looks right on the SE and on the Pro Max, the in-between sizes will too. Same logic for the tablets.

Reviewing previews

Open Previews in the app navigation. Each generated preview is a card with thumbnails for every device. Click a device thumbnail to open the full-resolution screenshot in a viewer.

What to look for:

• iPhone SE (320 px) — the narrowest mainstream viewport. If anything stays horizontal that should stack, you'll see it here first.
• iPhone 15 Pro Max — a typical "large modern phone." Most of your readers are on a viewport this size.
• iPad Pro 11 portrait — interesting because some emails switch to single-column layout at smaller widths but stay multi-column here.
• Landscape iPads — wider than desktop email containers (max ~600 px). Useful for catching layouts that assume "wide = desktop, narrow = mobile."

Common issues virtual previews catch:

• A button with width="200px" that overflows the column on small phones.
• A 2-column section that doesn't stack on mobile because of explicit pixel widths.
• A background image that's positioned correctly on desktop but cuts off the headline on mobile.
• A hero image that's stretched on iPad portrait because of mismatched padding.

What virtual previews can't catch

Things you still need to test by sending real mail:

• Gmail's CSS stripping — <style> blocks in <head> are partially honored, @font-face is dropped, embedded images can be blocked by default.
• Outlook desktop's table layout quirks — the Word-based renderer ignores most modern CSS, falls back to inline styles only, and has unique padding/border behavior.
• Dark-mode rendering — most clients invert colors in dark mode, sometimes badly. Virtual previews always render light mode (the system default in headless Chromium).
• Display blocking — most clients block images until the recipient explicitly allows them; previews always show images.

Treat virtual previews as a device-layout sanity check, not a comprehensive QA pass.

Storage

Each preview's screenshots are stored on EmailBuilder's CDN (DigitalOcean Spaces). They persist until you delete the preview from the Previews page. Storage doesn't count against your plan limits today, but heavy use over time may eventually do so — clean up old previews if you have hundreds.

When to generate

A virtual preview is overkill for routine edits — the in-editor mobile preview toggle (visible/hidden via a button in the canvas toolbar) shows you the same mobile width in real time, just with fewer device dimensions.

Generate a virtual preview when:

• You're about to send a campaign to a large list.
• You've made a substantial layout change (added columns, changed widths).
• You're working on a template that'll be used many times (a master newsletter template).
• You're reviewing someone else's template before approving it.

Plan limits

Generating a preview consumes one slot of the aiAssistant / preview job pool depending on what's involved — not a separate quota. Free Playground accounts can generate previews, but with the 1-minute job delay; Studio and Orchestra accounts get the same delay (admin accounts are an exception with a 10-second delay used for testing).

Cross-link

The companion is Send Test in the editor — that sends a real email to your inbox, where you can open it in actual clients. Use both: virtual previews for layout, send-tests for client-specific quirks.