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Inbox previews in Brew, rendered per client from a chat prompt
An email that looks perfect on the canvas can still break in a real inbox. Outlook mangles a table, dark mode inverts your logo, or a mobile client squeezes a two-column layout. Brew renders your design across real email clients and devices and returns a screenshot per client. That way you catch rendering issues before the send goes out. This works for any design, one-off Emails and automation emails alike.

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Run a Preview

1

Open a design on the canvas

Open any email. In the Preview panel on the right, switch to the Inboxes tab.
2

Pick your clients

Choose the default spread (Gmail, Outlook, Apple Mail, and iOS) or select specific clients, including OS, version, and light/dark mode combinations.
3

Review the results

Screenshots come back per client. Clients that are slow to render show as Pending. Click Retry to fetch only those without re-running the rest.
Each preview run costs 10 credits, charged only when at least one client renders. If nothing comes back, you aren’t billed.

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Supported Clients

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What to Check

  • Outlook first. Outlook on Windows uses its own rendering engine and is the most common place layouts break. Check tables, spacing, and background images there before anywhere else.
  • Dark mode. iOS and Apple Mail dark variants show whether your colors invert gracefully. Watch for logos that vanish on dark backgrounds and text that loses contrast.
  • Mobile. The iOS and Android variants confirm your layout stacks correctly on a narrow screen.

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Inbox Previews vs Test Sends

Each check answers a different question:
  • Inbox previews show how the design renders across many clients at once. You need no inbox accounts, and the results come back in one grid.
  • Test sends deliver the real email to your own address, so you can check the from name, subject, preview text, and links as an actual recipient.
  • Inbox placement tests send the real email from your verified domain to Brew’s seed inboxes and report, per mailbox provider, whether it reached the inbox or spam. Each test costs 10 credits. From an agent, create_inbox_placement_test starts one and get_inbox_placement_results reads it. Brew University walks through it.
A good habit: preview across inboxes while iterating. Run a placement test before a large send from a new domain. Then send yourself a test right before the real send.

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From an Agent or Code

The same feature is available programmatically:
  • API: POST /v1/emails/{emailId}/client-previews. Pass clients with ids from the supported catalogue, or an empty body for the default spread. It starts a rendering job and returns its previewId; poll GET /v1/emails/client-previews/{previewId} until the job finishes.
  • TypeScript SDK: brew.emails.previewClients({ emailId }) starts the job; poll brew.emails.getClientPreview(previewId).
  • MCP: the test_email_rendering tool, so agents can QA a design as part of a workflow. It returns a previewId right away, and the agent polls get_email_rendering with it until the screenshots are ready. Ask for a preview in chat and the screenshots come back in the conversation, with a link to each full-size render. For a free look at the design itself, get_email returns its preview.
Claude running a Brew inbox preview over MCP, returning Apple Mail and Gmail renders
See the API Reference for the full client catalogue and response shape.

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Need Help?

Our team is ready to support you at every step of your journey with Brew. Choose the option that works best for you:

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