@Alessandra852 An email shouldn't be necessary. If the host followed the procedure for requesting payment for damage, it will ha e come through Airbnb resolution center, with a link you need to follow directly in order to respond. Many people have reported that this feature doesn't work on the mobile app, so if necessary log into your Airbnb account on a desktop computer.
If you decline the claim, a case manager from Airbnb will get involved. Considering the high amount, the host will have to back his claim up with proof including timestamped photos and receipts. If this is a reputable host with many positive reviews, it would be unusual for them to make a false claim - so I wonder if there is a gap in the time line between your departure and the host's inspection when something like a water leak might have occurred. If you're certain that you left the property in the same state that you found it, it would be helpful to keep your communication peaceful and try to establish the relevant facts.