7.4.3 hosts and co-hosts agree that each activity , booking , or other transaction reported on the airbnb platform , including any co-host services provided by the co-host and any amounts due from a host to the co-host for the provision of such services , will be deemed accurate , correct and binding , unless challenged , by notifying the other person and airbnb -lrb- by emailing host-exp@airbnb.com -rrb- , within 21 days of posting of the disputed activity , booking or other transaction on the airbnb platform .