An Offline Storage File (OST) or Offline Data File format used by Microsoft Outlook to store the Email application data. Offline storage file is created when Microsoft Outlook used with Microsoft Exchange Server.
It also holds all Email messages, notes, journals, tasks, contacts and calendar in a single file.A local file created in a computer in Outlook data file named as Offline storage file. This file used when we work in Cache exchange mode or want to work offline, without connection with Microsoft Exchange Serve
Local OST File is the slave replica of Exchange server Mailbox. File get synchronized when a connection is available.
The OST file is only supported by the Microsoft Outlook When connected with Exchange Server in cache exchange mode
Application/vnd.ms-outlook
It has the following file signature:- hexadecimal 21 42 44 4e
To provide the facility to work with emails in ofline mode. Microsoft has introduced the concept of OST file format.
Microsoft Outlook 2016
C:\Users\%username%\Documents\Outlook Files.
Microsoft Outlook 2013
C:\Users\%username%\Documents\Outlook Files.
Microsoft Outlook 2010
C:\Documents and Settings\%username%\My Documents\Outlook Files
Microsoft Outlook 2007
C:\Users\%username%\AppData\Local\Microsoft\Outlook\
Microsoft Outlook 2003
C:\Documents and Settings\%username%\Local Settings\Application Data\Microsoft\Outlook\
Microsoft Outlook 2000
C:\Documents and Settings\%username%\Local Settings\Application Data\Microsoft\Outlook\
