public folder in Exchange

1. Start ADSI Edit. In the CN=Configuration container, locate the following container:
   CN=Services,CN=Microsoft Exchange,CN=ORGANIZATION,CN=Administrative Groups,CN=administrative_group,CN=Folder Hierarchies,CN=Public Folders
   Note In this container, ORGANIZATION is the name of the Exchange Server organization and administrative_group is the name of your administrative group.
2. Right-click CN=Public Folders, and then click Properties.
3. Click the Security tab.
4. Make sure that the Allow inheritable permissions from parent to propagate to this object check box is selected.
5. Make sure that the Everyone group has the following Allow permissions:
   • Create named properties in the information store
   • Create public folder
   • Create top level public folder
   If the Allow inheritable permissions from parent to propagate to this object check box is selected, the Everyone group should already have these permissions. Make sure that the Deny check boxes are not selected.

http://support.microsoft.com/kb/313866