This issue has been resolved in 5.7.1.
To do so you need to enable "Store access credentials for online Exchange." This allows Recovery Manager for Exchange to store access credentials (user name and password) with which you access online mailboxes or public folder hierarchies from within the Recovery Manager Console or Management Shell. With this check box selected, Recovery Manager for Exchange securely stores the access credentials you enter, so you do not have to enter them again next time you access the same online mailbox or public folder hierarchy.
