I use Microsoft Outlook 2007 with the Outlook Connector to sync my Live Mail accounts.The backup tool in Windows 7 will smartly backup the C:/Users/User/AppData/Local/Microsoft/Outlook/ folder's PST files. Yeah! Except for users like me using the Outlook connector, the meat is kept in an OST file (offline outlook cache file) while the PST file is a paltry few kilobytes of nothingness.Here's where it get worse. I can specifically add the entire Outlook appdata folder to the backup set & all the other cruddy xml and obi files get backed up, EXCEPT the OST cache file! The backup tool must be set to skip this file type. Is there any way to back this up?Even the additional download pack to add the backup functionality within Outlook applies only to PST files.My only options I see (neither are desirable):- auto archive emails in a PST which will be backed up- install a 3rd party backup that doesn't ignore OST filesAny help?

Firstly, we should understand the OST file is an offline folder file in Microsoft Outlook. Offline folders make it possible for the user to work offline and then to synchronize changes with the Exchange server the next time they connect. The ability to work offline is useful in environments with limited or unreliable connectivity. Maintaining changes to OST files within shadow copies is expensive in terms of space and I/O activity. The time-consuming work at backup time is backing up the OST files as part of the image. Everyday I/O will write to the OST file when Outlook is running. So the backup process will impact the performance on the computer. If the OST changes were kept in shadow copies, then Outlook writes to the OST files is copy on write I/O hit (2 writes, 1 read)every time. Even though we have worked to reduce the impact of copy-on-writes on shadow copies, a heavily churned file such as OST file still cause problems on the computer. In addition, the OST files can be regenerated. We delete OST file from the shadow copy before the image is created. For example, after restoring an OST, the computer detect a new version of the OST file on the computer, it will force you to delete, and the regenerate the local OST file. Therefore, it is still preferable to regenerate an OST file instead of restoring it. So, Backup the OST files is needless. If we backup the OST files on the computer, after restoring it by using the backup files, it will affect the computer stability and Outlook stability. If the computer restore it by using the old backup files, when starting Outlook, it will detect the computer has a old version, it will force you to delete the backup one, and then it will regenerate a new one on the computer. The Outlook will use the new one to startup normally.

Thanks for taking the time to respond. Your response was very thorough and helped me understand the reason behind why for most people backup of the OST file is not desirable.There is one thing I disagree with in my particular case (but not necessarily universally):"So, Backup the OST files is needless."There are two reasons why having a periodic backup of offline files, stored independendantly may be useful:1.the user deletes an email(s) accidentally 2.the server deletes an email(s) in errorIn my case, Live Mail had a server error which deleted yearsof valuable personal emails. The local cache was updated before I discovered the issue and there was no recourse to retrieve them.So, I think my solution will either to try to hack the backup tool to include OST files or just periodically save a copy of the cache myself manually. I think I learned an important lesson on taking the cloud for granted.

According to your description, you have a concern about what we should do if the emails were lost unexpected. Give this situation, we can turn on the AutoArchive in Outlook 2007 to achieve this efficiency. Use this method, we can backup our old emails. Outlook turns on AutoArchive by default to automatically archive old items on a set schedule. Outlook archives the following items: Outbox items older than three months Sent and Deleted items older than two months All other items including the Inbox, Calendar, Tasks, Notes, Journals and Drafts older than six months. We can follow the below link to set the configuration on How to Archive Outlook Email: How to Archive Outlook Email

Hello customer, By default, the .ost file is related to Exchange Server and is associated with a mailbox on the Exchange server. I would like you to know Microsoft does not offer the solution to open the orphan OST file due the security issues. 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. However, I understand the data is very important for you; therefore I suggest you copying all mails on the server into the local pst file or transfering there OST files manually. Thanks for your time and understanding! Hope the above information helpful! Andy