File corruption is a frequent hassle in Outlook, and many said that The folder can't be expanded. This occurs if your profile or setup is broken In some instances, new folders aren’t seen in Outlook, and if that happens, you may desire to attempt recreating them. the set of folders cannot be opened outlook 2016 This hassle can additionally show up if one or extra folders in your mailbox are named incorrectly, so be positive to take a look at that as well.