My computer slows down when Outlook shows the "Updating Address Book" status. In computers with slow hard disk drives, such as portable computers, or running Outlook in a Virtual machine, the process of updating the address book can slow down the computer if the hard disk is fragmented.

outlook 2016 oab not updating-4

” Well, the truth of the matter is that our new joiner Joe is in fact , an update to the Address Book won’t become available to the user until about 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.

In Cached Exchange Mode, Outlook 2007 & 2010 downloads a local copy of the Global Address List (GAL), but only updates it every 24 hours.

In order to reflect any changes or updates made to the Global Address List, you can force Outlook to download a new copy of the GAL.

Please visit the document on How to turn on or off Cached Exchange Mode for (Outlook 2010, and Outlook 20).

Outlook 2011 does not use Exchange Cached mode and directly connects to the Global Address Book (GAL) via LDAP connection.

Do send/receive settings affect automatic 24-hour offline address book downloads?

The Download offline address book check box in the Send/Receive Settings - "Group_name" dialog box does not affect the 24-hour download process.

When changes occur within the main Global Address Book (GAL) on the Office 365, computers running Outlook 20/2016 may not automatically receive the updates.

If this is happening, then you may notice missing, non-existent and/or incorrect entries.

*** NOTE: The GAL is essentially a real-time / online representation of AD Objects that are Mail Enabled for Microsoft Exchange *** The GAL contains information for all email enabled users, Distribution Groups, and Shared Mailboxes and Exchange Resource Mailboxes.