fromstringобязательный
From email address (e.g. "onboarding@resend.com" or "Resend onboarding@resend.com")
htmlstring
HTML version of the email content. Placeholders: {{{FIRST_NAME|fallback}}}, {{{LAST_NAME|fallback}}}, {{{EMAIL}}}, {{{RESEND_UNSUBSCRIBE_URL}}}.
Email HTML requirements — follow all of these without exception:
STRUCTURE
- Always include <!DOCTYPE html>, <html>, <head>, <body>
- Layout must be table-based: <table>, <tr>, <td> — never use <div> for layout
- Outer wrapper table at width="100%", inner content table at max 600px wide
- Every table must have cellpadding="0" cellspacing="0" border="0"
CSS
- All styles must be inline (style="...") — no <style> tag, no external stylesheets
- No flexbox, no grid, no CSS variables, no CSS shorthand (use padding-top not padding)
- font-family must always include web-safe fallbacks (Arial, Helvetica, Georgia, sans-serif)
- Always set font-size, line-height, and color explicitly on every text element
IMAGES
- Always set width, height, border="0", display:block on every <img>
- Use absolute URLs only — no relative paths
- Always include alt text
LINKS & BUTTONS
- Never use <button> — use <a> styled as a button inside a <td>
- No <video>, <form>, or <input> elements
- No JavaScript of any kind
OUTLOOK COMPATIBILITY
- Use bgcolor attribute on <td> alongside CSS background-color
- No CSS background-image (poor Outlook support)
- Add <!--[if mso]> conditionals where needed for Outlook rendering
META (in <head>)
- <meta charset="UTF-8">
- <meta name="viewport" content="width=device-width, initial-scale=1.0">
- <meta http-equiv="X-UA-Compatible" content="IE=edge">
namestringобязательный
Name for the broadcast. If the user does not provide a name, go ahead and create a descriptive name for them, based on the email subject/content and the context of your conversation.
previewTextstring
Preview text for the email
replyTostring[]
Reply-to email address(es)
segmentIdstringобязательный
Segment ID to send to
subjectstringобязательный
Email subject
textstring
Plain text version of the email content. The following placeholders may be used to personalize the email content: {{{FIRST_NAME|fallback}}}, {{{LAST_NAME|fallback}}}, {{{EMAIL}}}, {{{RESEND_UNSUBSCRIBE_URL}}}. If omitted, HTML will be used to generate it. Pass an empty string to disable automatic text generation.
