Convert OST to PST

Outlook for Microsoft 365, Outlook 2021, Outlook 2019, Outlook 2016, Outlook 2013

This tool converts Offline Outlook Data File (.ost) to Outlook data file (.pst). You can also use this guide to export OST file to PST files, in case of data loss on the mail server, or when you need to recover a deleted, orphaned or inaccessible OST file.

Offline Outlook Data File (.ost)

IMAP accounts, Microsoft 365 accounts, Exchange accounts, and accounts use an Offline Outlook Data File (.ost) file to store a synchronized copy of your mailbox information on your local computer. Any items that are saved locally will not sync. For example, Calendar, Contacts, Tasks, and any folders marked Local only.

Export or backup email, contacts, and calendar to an Outlook .pst file

When an OST file can be opened in Microsoft Outlook, you can use it to export items by creating a PST file. If you're using Cached Exchange Mode, Outlook will only export the items in your current cache. By default, Outlook configures Exchange and Microsoft 365 accounts to only synchronize 12 months of your email. Follow the export instructions to move your email from the OST file to a PST file. To export more than the past 12 months of data, turn off Cached Exchange Mode first.

How to convert OST to PST file?

If you have Outlook connection issues with mailbox on a server or cannot open your OST file, follow the steps below to recover the mailbox:

  1. Close Microsoft Outlook and all other mail-enabled applications that may use your Outlook mailbox.
  2. Download the software, and run it on your computer.
  3. Browse the OST file you want to convert and click Open.
  4. Preview all your items including email messages, calendar, contact, and task data..
    Convert PST data files to MSG format
  5. Select mailbox root folder in All Folders pane, and go to File > Export.
  6. Choose MSG as file format and All items in this folder and subfolders.
    Convert PST data files to MSG format
  7. Select destination folder and click Ok.
  8. Wait for the export to finish and click Ok.
  9. Import MSG files to PST file with MSG 2 PST.
    Convert PST data files to MSG format

After your email data is exported to a PST file, it's portable! You can save the .pst file to a portable drive; then open it with PST Viewer.

Online services to convert OST to PST

OST files contain your important and confidential data. When you use an online service to convert email from OST to PST, all of your sensitive data, including private messages, contacts, tasks and notes, is transferred to someone else's server. The data is processed on an unknown computer and you have no control over it. Only then will you be able to download the resulting PST file.

Unlike online converters, our utility works strictly on your computer. Information from the OST data file is not uploaded anywhere. Your data will not fall into the wrong hands.

Are there any limits when converting from OST to PST?

There is no limit on the number and size of the converted OST files and the resulting PST files. You can convert unlimited files as often as you like.

Bulk PST to MSG conversion

The program can bulk convert PST to MSG in batch scripts using PowerShell, Task Scheduler and other automation tools. To do this, use the command line options of the product.

pstwalker.exe [filename] [/E[:msg|umsg|eml] [/Name[:Id|EntryId|Subject]] [/PATH:folder] [/FullScan] [/HardDeleted] [/HardDeletedOnly]]

Specifies the .pst files to process. A filename mask can be applied, e.g. c:\source_folder\*.pst
Bulk extract messages to:
  • msg - .msg file format
  • umsg - unicode .msg file format
  • eml - .eml(rfc 822) file format
Naming style for the saved messages:
  • Id - incremental Id
  • EntryId - PR_ENTRYID (unique message identifier)
  • Subject - message subject
Specifies destination folder for bulk extracted messages
Extensive scan (to recover data from a damaged or a corrupted .pst, .ost files)
Find 'hard deleted' and 'orphaned' items
Export only 'hard deleted' and 'orphaned' items