Hey there, rachelbarrett912!

You'll be happy to know that you can absolutely get a record of that email that was sent to your customer through QuickBooks Online! It's actually really easy :) You'll want to start out by bringing up the actual invoice that you had emailed out. A fast way to get to it would be to click Customers on the left, click your customer's name, and then choose the Invoice from the list of transactions. You can see the date and time of the last send at the very top, under your customer's name. However, I want you to scroll all the way down to the very bottom. You should see the text you sent at the bottom of the screen, under the Activities header! Awesome!

Hope this helps you get you where you wanted to be, rachelbarrett912!