Outlook cached mode global address list not updating
At the very same time that I unchecked this "cached exchange" option on one workstation, another user reported that his address book had now showed the changes to the names on the address list (and this is after having changed the name on exchange server over 24 hours ago).
By default when you connect an Exchange mailbox to Outlook 2007 or Outlook 2010 the ‘Use Cached Exchange Mode’ option is enabled.
This should resolve the issue with users not showing up in Outlook when in cached mode.
The Global Address List (GAL) does not update on a Outlook client despite changes/new addresses appearing on other machines.
So log in to OWA and test if you can see the new users there.
I’m giving it a 99% chance that you will (and if you don’t you have a serious problem at hand!