Outlook cached mode address book not updating
This means that in the worst possible scenario, an update to the Address Book won’t become available to the user until 48 hours after the change.
This situation however is extremely rare since the default maintenance time on Exchange is at AM and updates and downloads are usually performed during working hours.
I’m giving it a 99% chance that you will (and if you don’t you have a serious problem at hand!
In outlook, click on the down arrow next to Send/receive. Note that if asked, you should select to download the entire address book and not just the changes.
This should resolve the issue with users not showing up in Outlook when in cached mode.
When you have Cached Exchange Mode enabled, Outlook by will by default cache the main Global Address List as well.
This is called the Offline Address Book and is being generated on the Exchange server.
Now, if you are like most organisations then outlook will be operating in cached mode.