Your source mail folders may contain characters or a format that MAPI cannot use when creating target folder names. However, we have found that with some versions of Outlook the problem disappears after rebooting the computer.
If this does not help, try renaming the source mail folder that is causing the problem or try using the alternate method convert email data to a PST file. Simply deselect the option “Process using Outlook (recommended)” under Target.
Should you require any assistance, please don’t hesitate to contact the help desk.