There is a setting in Sales Order Options which needs to be unchecked, in order to navigate to this setting please follow these instructions:
Click on the System Tab within Dimensions main window.
Click on Options in the Settings Section.
Select Sales Order Options from the list that appears, a new window will open.
Click on the Transactions Tab, at the bottom of this window, there is an option called ‘Always print a hard copy of invoices and credit notes.’ This is ticked by default.
Untick this checkbox. This will stop Dimensions from printing a hard copy of emailed invoices & credit notes.
Press the Save button.