An ost file extension is used for Microsoft Outlook Offline Folders files. The ost files are used to store e-mail messages and other data download from an Microsoft Exchange server. Microsoft Outlook Offline Folders files are very similar to Outlook personal folders files (.pst files).

Detailed description

Software that works with ost file extension

Add comment

Bookmark & share this page with others:

OST file extension - Microsoft Outlook inbox off-line folder

What is ost file? How to open ost files?

The ost file extension is associated with Microsoft Outlook, a personal information manager, which is part of Microsoft Office, developed by Microsoft Corporation.

An ost file stores e-mail messages and other data saved by the application from an Exchange server.

The ost files are very similar to the *.pst personal folder files, but do not support large file sizes.

The ost files are created when the "Use Offline Folders" option is checked in Outlook and are stored on the hard drive instead of the e-mail server.

Default location of ost files is:

Windows Vista, Windows 7, Windows 8, Windows 10

\Users\user\AppData\Local\Microsoft\Outlook

Windows XP or Windows Server 2003

\Documents and Settings\user\Local Settings\Application Data\Microsoft\Outlook

The default software associated to ost file type:

Microsoft Outlook icon

Microsoft Corporation logo Microsoft Outlook  Microsoft Windows software

Company or developer:
  Microsoft Corporation

Microsoft Outlook is e-mail management tool and personal information manager distributed with Microsoft Office suite. Outlook integrates e-mail application, calendar, task manager, contact manager, note taking in to one application.

Microsoft Outlook is used as a stand-alone application and also can work with Microsoft Exchange Server and SharePoint Server.

The predecessor of Outlook was called Schedule+. The newest version is called Outlook 2016.

Microsoft Outlook for Mac icon

Microsoft Corporation logo Microsoft Outlook for Mac  Apple macOS / Mac OS X software

Company or developer:
  Microsoft Corporation

Microsoft Outlook for Mac is e-mail client and personal information manager distributed with Microsoft Office for Mac. Outlook for Mac contains email, calendar, address book, task list, note list managers in one application. Microsoft Outlook for Mac is a successor of Microsoft Entourage for Mac.

Related articles:

How to set size limit for Outlook files

Help how to open OST files:

Use Microsoft Office Outlook to open/import Microsoft Outlook inbox off-line folder files.

How to convert file with extension OST:

Kernel for Exchange OST Recovery can recover emails from OST files and then converts them PST format using Microsoft Exchange 5.0, 5.5, 2000 and 2003.

Find conversions from ost file:

ost to msg

ost to pst

File identification strings:

HEX code: 21 42 44 4E
ASCII code: !BDNProgram

Related links:

Online Tutorial for Kernel Exchange OST Recovery

About Exchange Offline Folder (OST) file (detailed description)

List of software applications associated to the .ost file extension

Recommended software programs are sorted by OS platform (Windows, Mac OS X etc.) and possible program actions
that can be done with the file
: like open ost file, edit ost file, convert ost file, view ost file, play ost file etc. (if exist software for corresponding action in File-Extensions.org's database).

Hint:
Click on the tab below to simply browse between the application actions, to quickly get a list of recommended software, which is able to perform the specified software action, such as opening, editing or converting of the ost files.

  • Open ost file
  • Save ost file
  • Edit ost file
  • Create ost file
  • Import ost file
  • Export ost file
  • Recover ost file
  • Others ost file

Software that open ost file - Microsoft Outlook inbox off-line folder

Click on the link to get more information about listed programs for open ost file action.

Microsoft Windows:

Main software associated with ost file by default:
Microsoft Outlook small icon Microsoft Outlook
Other suggested software:
PstViewer Pro (EML Viewer Pro)

Apple macOS / Mac OS X:

Previous file extension
OPS file extension

File-Extensions.org > Various data file types

Next file extension
file extension PA

 

Follow us!

Enter any file extension without dot (e.g. pdf)
Search for file extension details and associated application(s)

RSS feed