Editing email body when sending invoices in "Reckon Accounts Easystart: First Business Edition 2014"

When sending invoices, an Outlook 2013 compose window opens, and there is already some text about paying the invoice, in the email body. How can I edit this text (template?) so that it says what I want and I won't have to manually edit is each time?

I am using Reckon Accounts Easystart: First Business Edition 2014 and Microsoft Outlook 2013, on Windows 8.