New Outlook instances seem to check a few minutes after startup. This is what worked for me when I had terribly-impatient users...
–For Instructions for Outlook 2007 –For Instructions for Outlook 2011 –For Common errors and troubleshooting Step 2: Uncheck the box next to Download changes since last Send/Receive.
In the Information to download section, select Full Details and in the Address Book section, choose \Global Address List. **NOTE** Please read this section carefully, or your update will not work!!
I saw this related question: Exchange 2010 offline address book does not update but the answer's blog post no longer exists.
If I create a new mailbox, and even if I manually update the OAB and then go into Outlook (in cached mode) and download OAB updates, it still doesn't show the new mailbox in Outlook 2010 until the next day.
Due to various synching schedules, it can take up to 48 hours before you could actually see a change in Outlook after a modification has been made on the Exchange server or in Active Directory.
In this guide, the relevant timings are explained and instructions are given in how you can directly force an update and resync, which can be very handy when troubleshooting or when you work in an Exchange environment which sees a lot of user mailbox mutations.
The command for the manual update procedure can be found here: Outlook will automatically download updates only unless the size of the changes is larger than 12.5% (one-eighth) of the total OAB size.
In that case the whole OAB is being downloaded again.
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.
If this is happening, then you may notice missing, non-existent and/or incorrect entries.