In many organizations, often there is poor communication between the human resources department and the system administration people. Reasons for this vary from company to company, but it is common for the system administrators to be some of the last people to learn that a person has changed departments or has left the company.
In SharePoint Server 2007, when a user account is deleted in Active Directory, that deletion is not implemented in the user profile database in SharePoint Server 2007. Even though the account is marked for deletion in the user profile database, the account must still be deleted manually by a SharePoint administrator. If you need to remove a user's profile from the user profile database before it is removed through a full import, you need to propagate policies to this effect. In this domain area, here are some issues to consider:
Worker status changes are sent to system administrators in a timely fashion.
Users must inform system administrators about changes in status.
Arrange for transfer of ownership of information after a user leaves the company.
Specify a schedule of file deletion after a user leaves the company.
User notifications need to be cleaned up by the SharePoint administrator.