Zoho invoice automation: How to automate sending of invoice email?

I have a requirement whereby I need to send out Zoho Invoice email from my zoho creator application i.e. the creator application generates invoices and emails them out (something I would manually do by going into the Zoho Invoice interface and click "Send Email" on the right of the invoice.

I have tried the integration tasks and there does not seem to be a method to accomplish this.

Any work around? Any hack?