Jan 22 · 4 min read · When people use Exchange Server, Office 365, or IMAP accounts in offline mode, Microsoft Outlook saves their mailbox data in OST (Offline Storage Table) files. OST files are good for syncing, but they can only be used with the original Outlook profil...
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Jan 16 · 4 min read · Microsoft Outlook is a popular email client for both personal and business use. When Outlook is connected to an Exchange, Microsoft 365, or IMAP server, it saves mailbox data on the computer in an OST (Offline Storage Table) file. This lets users wor...
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Dec 12, 2025 · 4 min read · What Is an OST File and Why Conversion Is Needed An OST (Offline Storage Table) file is created by Microsoft Outlook when users work in cached exchange mode. It allows access to emails even without an internet connection. However, OST files are tight...
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