A check for invoice has been sent or printed: symbol suggestion

Hello! Is there a way to see in the agenda if you have sent the invoice to the email of the client or that you printed out? Because a lot of time we miss this and it is very important for our clients that they receive the invoice. Suggestion: a certain symbol (like the black money notes when somebody has paid). Or when you clicked in the invoice on “save payment”…and that you can only leave that page, if you emailed or printed…otherwise you get a pop up and can not leave this screen before you clicked away the pop up and clicked email or print… Hope there is a solution for this! I know you can always see at Communications what has been sent, but it is a lot of work to count all of that at the end of the shift and has to puzzle who you missed and also in our case we see everything from our other location…Thank you!