Global address list is not updating
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.
Instances of mail that is bounced back to the sender may also be fixed.
Please use the steps below to update your Global Address Book.
We have another server in the wings waiting to be deployed, but we need to address the problem in the meantime. If it does not, then it is the generation or distribution process that is failing. OWA reflects the information correctly, but Outlook does not. I have tried deleting the OAB files, but when I download the address book, it still has the outdated version.
In that case, you can completely reset it by deleting the files making up the OAB or by recreating your mail profile.In order for some GAL entries to show up properly you may need to turn off Cached Exchange Mode.