'Excellent service, thank you!'
'The spread was beautiful and I am sure that My Aunt would have loved the flowers. Thank you so much.'
'Flowers were beautiful - fresh and lovely - they reflected exactly the love/loss of a special childhood friend which I felt in my mourning heart and which I couldn't express in words. Thank you.'
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.