If you fly frequently on Delta, you know by now that seat upgrades are far and fewer than they used to be.
So if you received an email that you've been upgraded, check the seat that the airline has assigned you. There is a decent chance that it's a middle seat. Check the Seat Map by clicking on the Seat Selection in the Delta app. Try to find a window or aisle seat.
Wait, did you think that the airline will honor your preferred seat selection in your Delta profile when you get upgraded? I wouldn't count on that.