I can provide information on how to view a sent email in QuickBooks Online (QBO), richardiford.
In QBO, there is no sent email section like you can see on Gmail or Yahoo. To be able to view the quotes that you've sent, here's what you'll need to do:
Click the Gear icon at the top.
Under Tools column, select Audit Log.
Click the Filter drop-down,then select User, Date and Events.
Click Apply.
Under EVENT column, look for Emailed Quote transaction.
Click on the View link under the HISTORY column.
Click the Show all option at the right corner to view more details.