**401 Unauthorized:**
- Token expired or revoked
- Token lacks required permissions (Read vs Write)
- Missing `Bearer ` prefix in Authorization header
**404 Not Found:**
- Broadcast/subscriber doesn't exist
- Wrong base URL (using sendbroadcast.net instead of your instance)
**422 Unprocessable Entity:**
- Missing required fields (subject, body for broadcasts)
- Invalid email format for subscribers
- Trying to update a sent broadcast
**Body format for broadcasts:**
- Must be valid HTML
- Use `
` for line breaks, `` for paragraphs
- Don't include ``, `
`, `` tags - Broadcast wraps content automatically