Hi All,We have pretty much completed the installation of Exchange 2007 apart from one problem - The OAB does not work.When we click the 'to' button in a new email, we get the following error:The connection to Microsoft Exchange is unavailable. Outlook must be online or connected to complete this action.However, if we carry out an explicit download of the address book (Tools > Send/Receive > Download Address Book) this completes without error.Heres the setup:Published via ISA 2006 SP1 using a single SAN certificateAll clients will be using Outlook 2007We are using RPC over HTTPAutodiscover service seems to be configured correctly (The tests within outlook report success)If I go to the OAB URL, I cannot log in - I am repeatedly prompted for username/password (Although not sure if this is excpected or not?)I have noticed that the OAB file folder (c:\program files\microsoft\exchange server\clientaccess\oab\<GUID>) is empty, apart from OAB.XML - I'm pretty sure this should have more files, also note the XML file is empty, apart from the XML root node and <oab></oab>update-globalAddressList and update-offlineAddressBook complete without errorSo, as far as I can see, this is down to either one of the following:Authentication problem with the /OAB folder - This has windows and basic enabledThe OAB is simply not being populated for some reasonAny help, advice, suggestions will be much appreciated!Thank you.

Hi,Did you check this issue in the internal environment?To understand that how the OAB files are generated and replicated to CAS for download, please view the below article:http://blogs.msdn.com/dgoldman/archive/2006/08/25/How-Exchange-2007-OAB-Files-are-replicated-to-a-Client-Access-Server-for-download.aspx Please first confirm whether Web Distribution is enabled by running get-offlineaddressbook |fl command in EMS. Then check mailbox store your client is residing on does has an OAB associated with it If the issue persists, please locate C:\Program files\Microsoft\Exchange Server\ExchangeOAB and C:\Program files\Microsoft\Exchange Server\Client Access\OAB to delete the subfolder. And 1. Open EMC->Organization Configuration->Mailbox 2. Under Offline Address Book tab, right click the Default Offline Address Book and click Update 3. Then, please check whether the subfolder is created under the below location on the OAB generate mailbox server: C:\Program files\Microsoft\Exchange Server\ExchangeOAB\ 4. If the OAB file is generated, please restart the Microsoft Exchange File Distribution service on the Client Access Server and then check whether the OAB file has been replicated to the C:\Program files\Microsoft\Exchange Server\Client Access\OAB on the Client Access Server. 5. If the OAB file has been replicated to the Microsoft\Exchange Server\Client Access\OAB, please logon on Outlook 2007 to check whether the OAB download issue still persists.ThanksAllen

Hi,Did you find any solution to your problem. as I am also having similar issue except if I see under GUID there are whole bunch of files (may be 100s) but still no luck. It keeps prompting me for user id and password and finally fails with ACL error.And I checked I do have the permission in IIS and physical GUID Folder as well.??I guess there is issue in IIS Permission. *Note- In OAB Application settings: I have following selectionsApplication name: OABStarting Point: <Default Web site>\OABExecute permissions: Script onlyApplication pool:MSExchangeAutodiscoverAppPoolThanks for your response in advance.

I resolved the problem.As guessed IIS was the culprit for Authentication issue.*Note- In OAB Application settings: I NOW have following selectionsApplication name: None (Grayed out, I removed the OAB application)Starting Point: <Default Web site>\OABExecute permissions: NoneApplication pool:None (Grayed out)