How to customize email body and subject and split it by invoice number/customer name?

Summary:Hi team,

We request some support in modifying the SJG Dunning letter (Reminder emails for unpaid invoices).

The email notification to customers/clients only receive very limited information from the email subject and body of email, so when they respond to AR admin support, they don't know which invoice number they are requesting support for.

They are asking for the SJG Dunning letter that's sent with the email notification to be modified to include additional information.

• Invoice Number in the subject line
• Invoice Number in the body
• Bank details in the body

Currently the email message looks like:

Subject: Overdue Invoice <Insert Invoice num> for Payment