I’ve got the steps you’ll need to be able to send estimates in QuickBooks Online (QBO).
To get started, let's configure your email setup. Here's how:
Go to the Gear icon at the top.
Choose Account and Settings.
In the left menu, click Company.
Click the Pencil icon for Contact info.
Clear the Company email address field and enter the desired address, even if it shows as the correct one. Make sure not to use any extra characters or spaces before, within, or after the address you enter.