I have created a new user and she is not showing up in the Global Address Book. You can send her an email successfully and she can reply. She shows up in Distribution Lists just not in the GAL. I am running Exchange 2010 with Outlook 2007 clients. I have rebuilt the OAB, and downloaded it again on the client side, still does not show up. It has been over 24 hours since I created the user and the OAB regenerates at 4am every night, so this shouldn't be the issue. I have made sure that the option under her mailbox to hide from Exchange lists is not checked. I have noticed for a couple users if I disable Cached exchange mode it will solve the issue, however this is not a solution to tell every user to disable Cached Exchange mode.