All clients use Outlook 2003 and our Exchange server is 2003.
I made an entry into the Global Address Lists named, "AMR" which has a filter rule. The filter rule examines the company within each user. If it starts with "AMR", the user should be included. Upon previewing the list, all of the users are displayed.
Unfortunately, two of the users are not being displayed on the Outlook clients. I have changed cached modes and that doesn't fix the issue. I have rebooted Outlook and the client machines - but that didn't fix it either.
In addition, within Exchange Server, i rebuilt the Offline Address Lists (the default one). this didn't fix it either.