CRM Quote/Invoice Email 'Send-to' Auto fill

CRM Quote/Invoice Email 'Send-to' Auto fill

Hi all,

I'm looking to find out two things - how to populate the dropdown of the email dropdown, and then how to automate this process, I have the email to fill out that field with.

My main requirement is to be able to get a lead from SalesIQ, manually convert to a contact when they confirm that they want a quote, then auto create an account (this part is done). Then I want to be able to create a quote which turns into an invoice when accepted (I've checked the setting that does this), but the send-to field only contains my account's email, none of the converted account's emails. I also can't manually write in this field.

So how do I populate the send-to field with the account's email? I don't want to have to choose from a list of 1000s of email addresses (but right now it is empty)

Many thanks,
Rob

Photo of the area I'm talking about:
https://i.imgur.com/M3G10sD.png