Send an email to one or more recipients through the Wunderkind email delivery platform to a subscribers
of the website id set by wunderkind.

This endpoint supports both HTML and plain text email content, custom sender information,
and flexible recipient management. All emails are processed synchronously.

Important Notes:

• All recipient email addresses must be valid and properly formatted
• The sender email address must be verified and susbcribed for the website id set by wunderkind
• If the email address is not subscribed, system silently ignores
• HTML content should be properly encoded and sanitized
• Large recipient lists may experience delayed processing