You can view the email history of an Invoice through both the Web Portal and the App.
In the Web Portal go to CRM > Invoices > sort by the Last Emailed column to find emailed Invoices..
Or
Select the Edit pen for the specific Invoice > Scroll down to the History/Notes. This will show all manual and automated emails that have been sent relating to this Invoice as well as edit history.
In the App go to Accounts > invoices > select the invoice that you would like to view > scroll down to History.
