How to turn off invoice issued notifications

This setting can be turned on or off from the Xero COnfig, MYOB config or Quickbooks Config (depending on what accounting package you have connected)

Once you have navigated to the Accounting Config tab depending on your connecting system, a screen will appear as shown below, and ensure that the checkbox under invoice-issued notifications is unchecked.

Once you have unchecked the setting make sure to hit "Save" to confirm the change.