Practice mail allows you to communicate with the ATO by a secure channel, as well as view messages you have sent or they have sent you.
Within your practice, you may also have access to more than one mailbox: your own, the practice’s or another person in the practice.
The ATO have found a significant number of tax professionals are only checking their assigned inbox, not their practice inbox. Make sure you set up notifications for your own mailbox and the practice mailbox to alert you when you receive practice mail messages from the ATO.