_MailItem.Categories Property (Microsoft.Office.Interop.Outlook)
Office 2007
Returns or sets a String (string in C#) representing the categories assigned to the Outlook item. Read/write.
Namespace: Microsoft.Office.Interop.Outlook
Assembly: Microsoft.Office.Interop.Outlook (in microsoft.office.interop.outlook.dll)
Assembly: Microsoft.Office.Interop.Outlook (in microsoft.office.interop.outlook.dll)