We rarely get them but have never had one bounce. And were will never mail until it clears.
Were always send a message to the buyer to tell them about what will happen.
Those who respond never know it has happened. Seems odd. We had one who bought two items and paid in separate transactions. One was echeque. When we messaged her she had no idea. Then she asked to cancel the echeque which we did. Then she paid again with instant payment. So I don't understand why these happen at all.