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OST/PST (no Outlook) Considerations

OST files are normally part of Microsoft Outlook and they are intended to be cache files. The OST file is dependent on the user account they were created for. Transend Migration Console will attempt to work around this dependency and convert from the OST file if it is possible. Similarly, OST files are subject to periodic corruption. Transend Migration Console cannot address all potential corruption issues. If you find corruption within the OST file we recommended that you use the Inbox Repair Wizard from Microsoft’s support web site. This tool will attempt to fix the corruption, but it may not make the OST file convertible. Therefore, if you have an OST file with corruption, then Transend Technical support will need a copy of the OST file in order to troubleshoot the issue for you.

Becasue your OST file is not easily portable, it is not reliable as a migration source. However, Transend Migrator will attempt to read the Message, Contacts, Calendars, and Tasks items from the OST file and convert them.

Outlook PST option

If you have a PST file you would like to migrate, but do not have access to an Outlook client, then you can select the OST/PST (no Outlook) option. However, if you have access to an Outlook client, we strongly recommend you select the Outlook PST option, as it is much more reliable.


  • Becasue this option does not use MAPI, Microsoft Outlook is not required in order to convert from an OST or PST file when using the OST/PST (no Outlook) option.
  • Microsoft Outlook stores local messages, contacts, calendars, and tasks inside a Personal Folders File (PST) or it caches data locally inside an Offline Folder File (OST). The OST and PST files are normally stored onto the local workstation.