The users manual for billing manager says to:

B. Customizing the Email Reminder
To customize the content of the email reminder to add your company logo, custom message, etc. you can modify the email html template “InvoiceEmailReminder.htm” located off your portal root directory in the /DesktopModules/SmithMerchantConsole folder.
The following email tokens are supported in the save cart email template:
[FIRSTNAME]
[LASTNAME]
[INVOICENUMBER]
[INVOICEDATE]
[LOGO]

problem... i don't have that folder, so where should the reminder template email go?