What "Reference" in Mail create a draft module is about?

What are you trying to achieve?

I try to ask ChatGPT to prepare a email draft when receiving new emails in my Gmail account. I successfully achieved it with my MS365 account, but can’t fix it with gmail requested fields. I cannot figure out how to map the mandatory field “reference” in my “create a draft” module. I don’t know what is waited for.

Steps taken so far

I have already try to insert the reference I

Screenshots: scenario setup, module configuration, errors