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Tuesday, April 23, 2024

How offline Address books works in Exchange 2010

For Users where Outlook is in Cache mode, They got to have their Outlook Address book when they are offline.

If Outlook is left running constantly in Cached Exchange Mode, it updates the Offline Address Book automatically about once a day, depending on Address Book updates on the server running Exchange. To initiate these updates manually, do the following:

  1. On the Tools menu, point to Send/Receive, and then click Download Address Book.
  2. Under Information to download, click Full Details or No Details.

So that they can use their updated address book when they are offline.

Earlier Exchange Versions Outlook Connects to the Mailbox Server for MAPI Connectivity.

But From Exchange 2010 Outlook Connects only to the Client Access Server for MAPI Connectivity.

Offline Address book Generation Server will be a Mailbox Server.

Where You can See Below the Generation Server (If all roles are installed on the Same box) The work flow remains the same


Offline Address book has Two Methods of Distribution.

For Outlook 2010, Outlook 2007, and Outlook 2003 SP2 clients it uses OAB version 4

1 .Web-Based distribution

2. Public Folder distribution

Earlier Version Like Outlook 2003, Offline address book are Downloaded via Public Folders ,

So If you don’t have Outlook 2003 In your Environment , you can go ahead and disable Public Folder Distribution

From Outlook 2007 , Outlook Downloads Offline Address book using the OAB Url from the IIS Manager(Web-Based Distribution)

Offline Address book Updates its self Depends on the update Scedule

** This Updates the Items only on th Mailbox Server ** Where Users Download offline address book from the Client Access Server

Now Depends on the Update Time LZX files will get updated on the Mailbox Server.

**Offline Address book data are saved in the form of LZX files**

They are located at

By Default – C:\Program Files\Microsoft\Exchange Server\V14\ExchangeOAB


Every OAB will have their own GUID value,

To Find the GUID Value of the Default Offline address book,

You can Customize the name of the oab as per your requirement

When Right Click on the Offline Address book if you Click on Update , The LZX files should get updated on Mailbox Server

** Data Modified Changes to Recent Date – Lzx files are updating **

Now Outlook 2003 Users should be able to download their Offline address books from Public Folders

Now here Goes the Web-Based Distribution much efficient and must faster.

Now These Files are Copied to the Client Access Server where Clients can download from the Client Access server

For that Reason this Folder is Shared where Client Access Server can access it and Copy it.


* Background Intelligent Transfer Service does this Job

They are not Copied much frequently, They Copy the LZX files to the Client Access server depends on the Polling Interval

You Can Find the Settings for the  Polling Interval as shown below –


By Default – The polling interval is 480 minutes

You can find the OAB url , which is used for web based Distribution. in the URLs tab

By Default internal URL doesn’t use HTTPS.

Microsoft Exchange File Distribution Services does this job in the Client Access Server

Now the Same Set of Offline address book files copies over to the Client Access Server

They are located at

By Default – C:\Program Files\Microsoft\Exchange Server\V14\ClientAccess\OAB


As Now Offline address book are web based You can find a OAB Virtual Directory in IIS


It Uses Windows authentication by Default.

To Confirm That Outlook 2007 and Outlook 2010 Clients are using Web Based Distribution

Hold your Ctrl Key and Right Click on the Outlook icon – Click on Test Email AutoConfiguraion

Now Using AutoDiscover , You can see the Offline Address book URL as listed below with the Correct Guid Value


Client will Download their Own OAB depends upon their “Client Settings in Database Properties”

By Default it will be empty – It means its downloading the Default offline address book  –

You can choose one. Cause at times it fixes the OAB download issue


If they have address book policies applied They would Dowload their own OAB


Great !!

You Learn’t How Offline Address book works in Exchange 2010

It applies to Exchange 2010 RTM,SP1,Sp2

Satheshwaran Manoharan
Satheshwaran Manoharanhttps://www.azure365pro.com
Award-winning Technology Leader with a wealth of experience running large teams and diversified industry exposure in cloud computing. From shipping lines to rolling stocks.In-depth expertise in driving cloud adoption strategies and modernizing systems to cloud native. Specialized in Microsoft Cloud, DevOps, and Microsoft 365 Stack and conducted numerous successful projects worldwide. Also, Acting as a Technical Advisor for various start-ups.

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  1. You wrote: “Client will Download their Own OAB depends upon their “Client Settings in Database Properties”

    That is true, but in your case it will not work since you don’t have an OAB specificed on the Database. You might want to change the picture you have published to show that 🙂

  2. Client will Download their Own OAB depends upon their “Client Settings in Database Properties”

    That is true, but in your case it will not work since you don’t have an OAB specificed on the Database. You might want to change that 🙂

  3. Here’s a question for you.
    In my installation, the IUSR account needs RX,W access to the /oab files, and everything under them.
    Every time I manually run the FDS to push out changes, file permissions are changed to from AUTHORITYIUSR: (I)(OI)(CI)(RX,W) to AUTHORITYIUSR:(I)(DENY)(R). This breaks OAB. I have to restore the previous permissions and restart IIS to make everything work again.
    Do you have any idea why FDS would do this? or why IUSR requires RX,W, I was under the impression that only system required RX,W. On my server the system account only has R access to those files.

  4. Hi Sathesh,

    Thanks for sharing a good and simple article which states about OAB generation and distribution in exchange 2010.

    I would like like to clarify few of my queries, if i am wrong please correct me.

    which is the service will help the client access server to copy the OAB files from mailbox server. whether it would be an BITS or Microsoft exchange file distribution service?

    How frequently outlook clients will automatically download OAB? If it once per day…is there is any automated mechanism for outlook clients (ie:working in cached mode) to fetch the updated OAB in a periodic manner ?

    Once again thanks for writing an good article.


  5. In my scnario, we have a OAB in cas server.Blut clients gets stuck to download OAB. Progress nerver iniates:( Pls help



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