Preview and test sends

Live preview

The preview renders the template on the server exactly like the sender does – same Handlebars engine, same escaping, sanitizer and CSS inlining – using the values from the Sample data panel. Nothing is sent and no credit is used. On the Free plan the preview also shows the “Sent via Frontmail” footer.

Device: Desktop / Mobile switches the preview width (desktop up to about 820 px, mobile 375 px).
Color scheme: Light / Dark shows how your email looks when the mail app prefers a dark scheme (it applies your prefers-color-scheme styles).
Version: HTML / Text shows the plain-text version that is sent alongside the HTML.

Sample values come from each parameter’s Sample value (or Default value) in the schema. Change them in Sample data to test conditions and loops – for example, add three items to a list parameter to check the table layout, or clear an optional parameter to see the fallback. Sample data is never sent with real emails.

Below the preview, Checks lists errors and warnings – invalid Handlebars syntax, parameters used but not defined (or defined but unused), images without alt, a missing subject or recipient, an email over ~100 kB that Gmail would clip, and more. Errors must be fixed before you can save.

Test sends

Click Send test, enter an address in Send to and optionally pick a different Service (by default the template’s service). The dialog shows how many test emails are left today.

Test sends are free – they don’t use credits and don’t count toward your quota.
Each organization can send 20 test emails per day (reset at midnight UTC), and one person at most 10 per minute. Above the daily limit the editor shows test_send_limit.
Test sends use the current, unsaved editor content and your sample data, so you can try changes before saving.
The subject is prefixed with [Test] and the email goes only to the address you entered – CC and BCC are skipped.
They appear in History marked as test (use the Test emails filter to show or hide them).
The template’s auto-reply is not triggered and no contact is collected.
Sending requires a verified email address on your account.

If a test send fails, the error from the provider is shown right in the editor – usually a sender/domain verification problem. See the guide for your provider.

Checklist before going live

Preview on mobile and in dark mode.
Test send to Gmail and Outlook (they render differently).
No template check warnings (missing params, missing alt, size over 100 kB).
Required params and rules match your form.
Require CAPTCHA (Turnstile) is on and allowed websites are set for public-key templates.