As described in the first post in this series, the Drop Off Library is created when you activate the Content Organizer feature. As soon as you configure the Content Organizer to start routing documents (which, actually it does when you activate the feature), all uploads to the site are automatically sent to the Drop Off Library. It is just a typical SharePoint document library with a timer job that will process outstanding items. Whenever you create a rule and select a content type, the Content Organizer checks to see if that content type has been added to the Drop Off Library yet. If it hasn't, the type is added to the library so that when the edit form is displayed after an item has been uploaded, users can select any one of the content types that are used in the routing rules.
A standard document library was used because it allows one to take advantage of all the typical document library features, such as:
· Workflow - users can start workflows on items in the Drop Off Library to approve a document, for example, before it is routed
· Content Approval - items can be forced through a content approval process prior to it being routed
· Check In / Check Out - allows items to stay in the Drop Off Library until all required properties for the content type have been filled out. Once the properties are all completed though, items are routed whether or not they are checked in.
· Alerts - get notified when a new item is added to the Drop Off Library
· Permissions - create custom permissions for the drop off library. If you have set the Redirect Users to the Drop Off Library property in the Content Organizer settings, then this allows you to effectively control who can upload content in the entire site, since all uploads get routed to the Drop Off Library.