The OST file helps the user to work offline in case the Exchange Server is not available. This Outlook Data (.ost) file holds the entire Outlook mailbox information since the time of the last synchronization with the server. Offline Storage Table or OST is the Outlook Data file that is the exact copy of a user’s mailbox on the Exchange Server that is locally stored on the PC/system. In addition, you’ll find some methods that can help in reducing the size of OST file. In this post, we’ll discuss some reasons ‘why OST file is larger than the mailbox’ and issues that may arise due to a large OST file. that may result in larger OST file size than the mailbox. The mailbox items make up for a major chunk of OST file size but it also includes some other items such as public folders, hidden items, etc. Summary: Outlook Offline Data (OST) file stores all the mailbox data of a user locally on the computer.
