Troubleshooter: Understanding IMF's Interaction with Public Folders

Does Exchange Intelligent Message Filter (IMF) filter out spam messages that are addressed to mail-enabled public folders?

No. The IMF functionality that moves messages while they're in the Store depends on the existence of a client-created Safe Senders list or mailbox attributes that are created when a Microsoft Office Outlook 2003 or Outlook Web Access (OWA) client modifies the recipient mailbox's Junk E-mail Filter settings. Because mail-enabled public folders lack such attributes, IMF has no way to move messages for those folders. Therefore, IMF will set a spam confidence level (SCL) property for incoming messages that are addressed to public folders, but the Store won't take any action based on that SCL. (For more information about IMF, see "Deploying Exchange Intelligent Message Filter," September 2004, InstantDoc ID 43151.)