<a href=”http://technet.microsoft.com/en-us/library/aa997252.aspx”>Direct push</a> is what the active sync on Exchange 2007 does. This directly pushes mail to windows mobile devices without them having to plug into their PC to sync. If active sync is configured the way you want then it will work with all enabled users who have a windows mobile device. By default direct push is enabled in Exchange 2007 and all users are enabled for active sync on Exchange 2007. Are you getting an error when you attempt to sync a windows mobile device?