'Thank you very much...I was glad to hear that you got them there early...'
'I sent them several hundred miles from where I am located so I hope they were nice since I was not able to see them. The convenience was great'
'Thanks for the delivery advice. As it all worked as it says on the 'tin' I can't see how you can improve. Many thanks'
You won't be able to dismiss this by usual means (escape or click button), but you can close it programatically based on user choices or actions.