An offline address book (OAB) is a copy of an address list collection that’s been downloaded so a Microsoft Outlook user can access the address book while disconnected from the server. Microsoft Exchange generates the new OAB files and then compresses the files and places them on a local share. You can decide which address lists are made available to users who work offline, and you can also configure the method by which the address books are distributed.

1. Go to Send / Receive – Send/receive Groups – Download Address Book.

2. Make sure that “DOWNLOAD CHANGES SINCE LAST SEND/RECEIVE” is unchecked.  Then click on OK.

3. When the Outlook Send/Receive Progress window disappears, the address book will be done downloading.

Note: If you receive an error, please make sure that your Autodiscover CNAME record has been successfully created and configured.

Another way to make sure that you get a fresh copy of the OAB is by renaming the oab-files to .old when Outlook is closed.

They are stored in the following location:

• Windows XP
  C:\Documents and Settings\%username%\Local Settings\Application Data\Microsoft\Outlook\
• Windows Vista, Windows 7, Windows 8 and Windows 10
  C:\Users\%username%\AppData\Local\Microsoft\Outlook

You can paste the path mentioned above in the Address Bar of Explorer to quickly open the location.

When you are using Outlook 2010, Outlook 2013 or Outlook 2016, you’ll find a folder called Offline Address Books which itself holds subfolders with named after Account GUIDs. When you have multiple Exchange accounts configured, you’ll find a folder for each account that you have. The quickest and most thorough method is to simply rename the Offline Address Books folder by appending .old behind it.

When you use Outlook 2007 or previous, you’ll have to rename the individual oab-files instead. There are 6 of them:

uanrdex.oab
ubrowse.oab
udetails.oab
updndex.oab
urdndex.oab
utmplsts.oab
After deleting the files, make sure you trigger a manual update from within Outlook as described above.

Note: The “u” in front of each file name stands for “Unicode”. If you are still using Outlook 2002/XP or earlier, the file names are not prefixed with a “u” as the OAB files are stored in ANSI format.

Method #3 – Recreate Mail Profile

Re-add your account in a new mail profile. This will force and re-download everything.