Test send, mobile preview, and spam score

Before you send to your audience, the composer has three preview tools to catch problems early.

Test send:
• Click "Send test" in the composer
• Enter one or more email addresses (comma-separated)
• Test sends use the actual send pipeline (Resend, your sending domain, full personalization) so what you see is what recipients get
• Test sends do NOT count toward your audience or trigger journey enrollments
• Up to 5 recipients per test

Mobile vs desktop preview:
• Toggle the preview frame between desktop and mobile widths
• Many email designs that look great at 600px wide collapse awkwardly on a 320px phone screen — fix it before sending
• Touch targets (buttons) should be at least 44px tall

Inbox preview (Litmus-style):
• Click "Inbox preview" to open a modal with simulated chrome for:
◦ Gmail Web
◦ Apple Mail (macOS)
◦ Outlook Desktop
◦ Gmail Mobile
• Each preview renders the actual HTML inside the simulated client wrapper so you can see how subject, preheader, and first paragraph appear in the inbox list

Spam score (100-point):
• Same modal includes a 100-point spam-score panel
• Heuristics applied locally (no external API call):
◦ Trigger words in subject ("FREE", "ACT NOW", "guaranteed")
◦ All-caps subject
◦ Excessive punctuation ("!!!" or "???")
◦ Body word count too low (<50) or too high (>2000)
◦ Missing unsubscribe link
◦ Missing physical address
◦ Image-to-text ratio
• Each issue has a fix suggestion
• A score above 70 is a warning; above 85 is a hard recommendation to fix before sending

The preview tools surface problems before recipients ever see the campaign — use them as a final gate before Review & send.