I created a security group in Active Directory (AD), but I can't use it to set permissions on an Exchange 2000 Server public folder. In Outlook, when I click Add on the folder's Permissions tab, all I can see are users and distribution groups. What am I missing?

Try using Exchange System Manager (ESM) instead of Outlook to set the folder permissions. When you're on the Permissions tab for the folder, click Directory Rights, and you'll see your security group.

If you're running AD in native mode, you can also use a Universal Distribution Group, which lets you set client permissions as you would with other mail-enabled users. The Microsoft article "XADM: You Cannot Add a Distribution Group to Permissions of a Public Folder in Exchange 2000" (http://support.microsoft.com/default.aspx?sid=kb;en-us;q274046) explains the process. For more information about distribution lists, see Jason Seim, "Distribution Lists in Exchange 2000," February 2002, InstantDoc ID 23480.