Help !! I need to recover some old emails and all I have is a .ost file. When I try to open the outlook.ost file in Outlook, I get the message "outlook.ost file cannot be accessed because it has been configured for use with a diffeent mailbox"...Could it be that the GUID key is not the same in the Exchange mailbox as it is in the .ost file ? Is there any way to fix this ? I am trying to retrieve email from a user that was removed from AD. I went into AD and added the user back in and also a new mailbox was created for the user..BUt I'm guessing that this mailbox somehow does not relate to the .ost file for that user ?????

-Please let me know the mailbox of that user already present? or even the mailbox has been deleted?-Also check if you have the backup of your database, as you can then use the Recovery Storage Group and then restore that user's mailbox-Check out the steps mentioned in this link: http://www.windowsreference.com/ms-office/how-to-convert-ost-to-pst-format-for-outlook/ -You can also try to use some 3rd party tool to convert OST into PST-Some examples would behttp://www.convertost.com/http://www.convertost.net/http://www.recovermails.com/http://www.recoverytoolbox.com/recover_data_from_ost_file.htmlhttp://www.officerecovery.com/exchange/product_information.htm

Hi MS Kho, Please try to give the third party tools as Harpreet suggested if you want to convert OST to PST, Microsoft doesnt offer the solution to open orphan OST file due to security reasons Explanation: OST file is related to Exchange Server and associated with a mailbox on it. To keep the OST secure, Exchange and Outlook store a key derived from the mailbox's unique entry ID as part of the user's profile. If the user's profile doesn't point to that particular mailbox, the user can't unlock the OST. There is no method to open the standalone OST file directly in Outlook since it is encrypted with the Exchange server mailbox. You need to connect the OST file to the original Exchange mailbox, read the content and move the information to the PST file So, you shall try to restore the old mailbox by using Recovery Storage Group as Harpreet said combined with Emerge to extract the data More info: You cannot add offline folder (.ost) files to Exchange Server profiles in Outlook 2007 and in Outlook 2003 Restoring from an OST after Deleting the Mailbox [If users old mail profile still exists and unmodified] I also researched on the web and found some free OST2PST tools for you Note: The third-party products discussed in this post are not manufactured by Microsoft, vendor independent of Microsoft; we make no warranty, implied or otherwise, regarding these products' performance or reliability

MS Exchange Server and Outlook uses a key to secure ost file, this key has been verified every time you try to access the ost file. As the original mailbox is being removed from the server, and you recreated it, that's why the new mailbox can not authenticate the older ost file as the key for both mailboxes will be different. The only way to access the Outlook ost file you have is to convert it into a PST file, using third party convert ost to pst tool . Such tools converts Outlook ost to pst file that can be accessed with Outlook directly. Such tools are read only, that means they convert ost to pst file without altering anything in the existing ost file.

Professional OST to PST Migration tool successfully migrate ost emails to pst emails created using MS Exchange 5.0, 5.5, 2000,2003 and 2007. Advance OST to PST Conversion tool can effectively recover exchange emails or messages that have been deleted from Deleted Items folder. Visit us our site http://www.exchangeostrecovery.org/ Free Download http://www.systoolsdl.com/get.php?id=50

I gathered some related informatio from http://tech-twitt.blogspot.com/

Outlook .ost file can only be accessed with the account that created it. Cause of the erroe message "outlook.ost file cannot be accessed because it has been configured for use with a diffeent mailbox" is either the account that created the ost file is not accessible or is being removed. To access such ost files convert ost to pst file and import the resulting pst file directly in outlook using Import/Export option in th emenu bar of outlook.

Hi MS Kho To access an ost file without an exchange mailbox account youu need to convert ost to pst file, for converting ost fiel to pst fiel you can use third party tools.

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That is by design, there is an encryption key that is stored on the outlook profile in the registry as well as the corresponding key in the mailbox. They could differ for multiple reasons, you restored a mailbox, you created an ost on another machine etc. The article explains as well as how to backup the key. Considerations and best practices when resetting an Exchange mailbox database http://support.microsoft.com/kb/282496James Chong MCITP | EA | EMA; MCSE | M+, S+ Security+, Project+, ITIL msexchangetips.blogspot.com