If you’re using a service account for example your backup software, it’s some times nessesary that this account has full controll permissions on all the mailboxes in your Exchange environment. Now you can set the full controll permissions on all the mailboxes, but it’s better to set the permissions on your information store. So if there are new mailboxes created, they have also the right permissions automatically. With the following command you can set the permissions on information store level:
get-mailboxserver Servername | add-adpermission -user svc-backup -accessrights GenericRead, GenericWrite -extendedrights Send-As, Receive-As, ms-Exch-Store-Admin