OST to Exchange Migration
Exchange Server does not natively import an arbitrary offline or orphaned OST file. Microsoft's native mailbox import workflow uses PST files. If the original Exchange mailbox is still available, reconnect Outlook and allow it to rebuild the OST from the server. If required data exists only in an offline or orphaned OST, EdbMails OST to Exchange migrator can read the OST and migrate recoverable data directly to an Exchange Server mailbox without PST staging.
An OST file is an offline copy of an Exchange mailbox used by Outlook in Cached Exchange Mode. If the original Exchange mailbox is still available, Outlook can normally reconnect to the mailbox and create a new OST file. See how to rebuild an OST file. Direct OST-to-Exchange migration is mainly required when important mailbox data must be recovered from an offline, orphaned, inaccessible, or readable damaged OST file.
Exchange Server does not provide a normal native workflow to attach or directly import an arbitrary orphaned OST file. Microsoft's native mailbox import process uses PST files. EdbMails OST to Exchange migrator provides a direct workflow to scan the source OST, preview recoverable mailbox data, select required folders, map the source to the target Exchange mailbox, and migrate selected data without PST staging.
EdbMails supports source-to-target mailbox mapping for the migration. Automated mailbox mapping reduces manual mapping effort, while manual mapping is available when required. You can also download the free trial to evaluate the workflow.
Native PST Import vs Direct OST Migration
| Migration path | Source format | When to use |
|---|---|---|
| Exchange Mailbox Import Request | PST | Use Microsoft's native Exchange workflow when the source data is already available as a PST file. |
| EdbMails direct migration | OST | Use when required mailbox data must be recovered or migrated directly from an offline or orphaned OST file to Exchange Server. |
If you need a PST file instead of direct Exchange migration, convert OST to PST instead.
Outlook and Exchange do not provide a normal attach/import workflow for an arbitrary orphaned OST file.
OST to Exchange Migration Playbook
| Step | Purpose | Acceptance check |
|---|---|---|
| Identify source | Confirm whether the OST is active, orphaned or damaged. | Preserve a copy before changing an old profile/cache. |
| Prepare target | Confirm the correct Exchange mailbox, quota and approved access. | Sign in and verify target-folder access. |
| Define scope | Select required folders, date range and item types. | Document scope before the migration starts. |
| Run pilot | Test a representative set of items. | Check placement, dates, attachments, contacts and calendar. |
| Complete and review | Process approved scope and check logs. | Record exceptions and final status. |
This page covers direct Exchange migration from an OST file. For a portable PST outcome instead, see the PST conversion option above.
