Of course, by default, the language of the folder names will match the language of Outlook that you installed. Matching the folder names with the language of Outlook Manually renaming the folders via MFCMAPI.Changing the folder language of Exchange accounts via Outlook on the Web (OWA).Matching the folder names with the language of Outlook.Still, there are valid reason why you want to rename these folders with language differences between the folders and the Outlook interface being the most common. The reasoning behind this is mainly based on standardization and to prevent accidental renaming. The “Rename Folder” option for these folders is simply disabled (grayed out). Outlook doesn’t allow you to change the names of the default Outlook folders such as your Inbox, Sent Items, Calendar and Contacts folder.