What is OST file?

An OST (Offline Storage Table) file is a data file created by Microsoft Outlook when it's configured to work in offline mode with an Exchange Server. It stores a copy of mailbox items such as emails, contacts, calendars, tasks, and more, allowing users to access and work with their Outlook data even when offline. OST files synchronize with the Exchange Server when the internet connection is restored. They are essential for users who need to access their Outlook data offline or in scenarios where internet connectivity is unreliable. Additionally, OST files facilitate seamless access to Outlook data across multiple devices.