Exchange application has this amazing facility of creating an offline file which is synched with the respective Exchange account mailbox. But the existence of this OST file is limited and restricted to few conditions. File integrity is one of the common conditions for all the file formats; similarly any corruption in OST file restricts its smooth access. But it is not about corruption only, some OST files becomes inaccessible when they are orphaned as well. Let us see what an orphan OST file is;
Why OST File Becomes Inaccessible?
Exchange application binds the OST file to a particular MAPI profile. Its access is thus bound to some conditions like authentication of profile which was used to create that particular OST file. If this is not done, client application (i.e. Outlook) will not open Exchange OST file and throw errors. Thus to access OST file, you will need an active, non-dismounted, non-deleted Exchange profile to which OST file belongs. This happens because every Exchange mailbox creates a unique ID which can be accessed only when connected to server. This unique ID again generates an encrypted cookie in registry. When offline connection is made, profile will authenticate that the cookie exists or not. If profile is unavailable, OST throws error with warning message that connection to server is essential to recreate cookie. If the server account is unavailable, or you accidentally changed MAPI or domain settings, OST file will become orphan.
Potential Solutions for OST File Inaccessibility
If the condition states that the MAPI or domain settings have been accidentally deleted or changed, you can follow the below mentioned workaround methods to resolve the situation;
- You can try to connect Outlook application with the original MAPI
- Connect that MAPI address to original MS Exchange Server
If the re-establishment of synchronization between OST file and server is possible in your case, you can easily make the inaccessible OST file accessible again. However, it is possible only if you have the original MAPI address. In case you are not having the original MAPI address, you can go for a third party solution like OST Recovery, which will let you convert OST file to PST file. Software has an amazing recovery mechanism which helps to recover emails from orphan OST file to PST file. This converted PST file can be accessed without any conditions or bindings and one can easily view data of orphaned Exchange OST file.