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Export an Exchange Online mailbox to PST

At the end you will have a PST copy of one or more mailboxes, made either centrally by an admin through Microsoft Purview eDiscovery or on a user's PC with Outlook for Windows.

Updated 8 steps7 official sources
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Before you start

What you need before step 1

Applies to: Exchange Online mailboxes; Microsoft Purview eDiscovery (current experience) and classic and new Outlook for Windows, as documented by Microsoft

Admin roles you need

  • eDiscovery route: member of the eDiscovery Manager role group in Microsoft Purview (it includes the Case Management, Compliance Search and Export roles)
  • To add people to that role group: Organization Management role group, or the Role Management role
  • Outlook route: no admin role; Outlook must be signed in to the mailbox you export

Licences

  • eDiscovery route: Microsoft says to assign the eDiscovery user a Microsoft 365 Enterprise E3 or E5 licence
  • Outlook route: classic Outlook for Windows (included in Microsoft 365 Apps) or new Outlook for Windows

Web portals you will use (nothing to install)

Microsoft Purview portalUse the latest Microsoft Edge; exports download in the browserhttps://purview.microsoft.comOpen

Also have ready

  • Enough disk space for the export; eDiscovery splits PSTs at 10 GB
  • An archive tool such as 7-Zip or WinZip; Microsoft advises against the built-in Windows .zip utility for export packages
  • Browser set to allow pop-ups and automatic downloads from Microsoft Purview, with tracking prevention turned off for the site
Step by step

8 steps

  1. 1

    Add yourself to eDiscovery Manager

    Where: Microsoft Purview portal > Settings > Role groups

    On Role groups for Microsoft Purview solutions select eDiscovery Manager, then Edit. Under Manage eDiscovery Manager select Choose users, find and tick your account, select Select, then Next. Select Next and Save, then Done.

    You should see: Your account is listed as a member of eDiscovery Manager, and the eDiscovery solution card shows Cases.
  2. 2

    Create a case

    Where: Microsoft Purview portal > eDiscovery > Cases

    Select Create case. Enter a unique Case name (for example Export-annb-2026) and an optional description. Select Create.

    You should see: The case opens on its Searches tab.
  3. 3

    Create a search and add the mailbox

    Where: Microsoft Purview portal > eDiscovery > Cases > your case > Searches

    Select Create a search, enter a unique Search name and select Create. On the Query tab add data sources: search for the user and select their mailbox. Select Save. Leave the condition builder empty to collect everything, or add keywords or a date range to narrow it.

    You should see: The Query tab lists the user as a data source.
  4. 4

    Run the query

    Where: Same search, Query tab

    Select Run query and choose Statistics. Microsoft warns that an empty keyword condition returns every item in every selected source, so check the size before exporting.

    You should see: A statistics summary shows the item count and size for the mailbox.
  5. 5

    Export as PST

    Where: Same search > Export

    Select Export. Enter an Export name. Choose the items to include (indexed items, and optionally partially indexed items). Set Export type to Export items with items report and Export format to Create PSTs for messages. Tick Organize data from different locations into separate folders or PSTs to get one PST per mailbox. Choose a PST package size (1, 2, 5 or 10 GB) and .zip package size. Select Export, then OK.

    You should see: A confirmation dialog appears and the export starts as a process.
  6. 6

    Download the export packages

    Where: Microsoft Purview portal > eDiscovery > your case > Process manager (or the Exports tab), in Microsoft Edge

    Open the Export process. On the Overview tab, in Export packages, select the package and select Download packages. Allow the pop-up. Extract the .zip with 7-Zip or similar. Microsoft notes the older Microsoft Office 365 eDiscovery Export Tool is being retired; downloads now happen in the browser.

    You should see: A .zip downloads containing a PST named after the mailbox (for example annb@contoso.com.pst) plus the items report.
  7. 7

    Or export from classic Outlook for Windows

    Where: Classic Outlook for Windows on the user's PC, signed in to the mailbox

    Wait until all mail has downloaded. Select File > Open & Export > Import/Export. Select Export to a file, then Next. Select Outlook Data File (.pst), then Next. Select the mailbox (top-level folder) to export and select Next. Choose a location and file name and select Finish. Enter and confirm a password if you want one, then select OK.

    You should see: Outlook shows export progress, then a .pst file appears at the location you chose.
  8. 8

    Or export from new Outlook for Windows

    Where: New Outlook for Windows > Settings > Files > Export

    Go to Settings > Files > Export, select Get started and follow the wizard. Microsoft notes calendar and contact items saved in .pst files are not available in new Outlook yet, so use classic Outlook if you need them.

    You should see: The wizard finishes and saves a .pst file.
From experience

Expert tips

Choose eDiscovery for admins, Outlook for one-offs

eDiscovery exports centrally without the user's password or PC, handles many mailboxes at once and gives an items report you can reconcile. Outlook export suits a single user exporting their own mailbox, but only exports what has downloaded, so wait for full sync first. New Outlook cannot yet use calendar and contact items in PSTs, so use classic Outlook when those matter.

Run Statistics and split large exports

An empty query returns every item in every source. Check the size with Run query > Statistics first. Microsoft cancels exports running longer than seven days and limits one export to 500,000 items, so split large mailboxes into date ranges before you start rather than after a cancelled run.

Include partially indexed items when you need a full copy

Items such as encrypted messages or unsupported attachments may be only partially indexed. If the PST is a full backup before migration or decommissioning, include partially indexed items in the export so they are not silently left behind; compare the items report with the statistics afterwards.

One PST per mailbox, extracted with 7-Zip

Tick Organize data from different locations into separate folders or PSTs so each mailbox gets its own PST named after it. PSTs split at 10 GB. Extract with 7-Zip or similar rather than the built-in Windows zip tool, and turn on condensed paths if deep folders hit path length limits.

Download within 14 days and treat PSTs as sensitive

Export packages are deleted 14 days after creation, so download promptly. A PST holds a whole mailbox: store it encrypted or password-protected, restrict access, and delete it when no longer needed. Remember that deleting the case also removes any holds you placed in it.

Check it worked

How to confirm it worked

  • Open the PST in classic Outlook and check that the folders and item counts match the mailbox.

  • For eDiscovery exports, compare the items report in the package with the search statistics.

Undo

How to reverse it

Rollback:

Exporting does not change the mailbox, so there is nothing to roll back. Delete the PST files when finished, as they contain the whole mailbox. eDiscovery export packages are deleted automatically 14 days after creation. Closing or deleting the case turns off any holds in it, which releases held content.

Troubleshooting

Errors you might see

The file name(s) would be too long for the destination folder. You can shorten the file name and try again.

Cause: Deep folder paths in the export package exceed Windows path limits when unzipping.

Fix: Turn on the option to condense paths when exporting, or extract with 7-Zip.

Download does nothing or is blocked

Cause: Pop-ups, automatic downloads, cookies or tracking prevention are blocked for Microsoft Purview.

Fix: In Edge, allow pop-ups and automatic downloads for the Purview site, allow cookies for the eDiscovery proxy domain and turn off tracking prevention for the site.

Export cancelled automatically

Cause: Microsoft cancels exports that run for more than seven days.

Fix: Split the export into smaller searches, for example by date range.

Export package no longer available

Cause: Search export packages expire 14 days after creation and are deleted.

Fix: Run the export again.

FAQ

Questions

How large can an eDiscovery PST be?

Microsoft lists a maximum PST size of 10 GB; larger results are split into multiple PSTs automatically. One export can hold up to 500,000 items.

Can I get one PST per mailbox?

Yes. Tick Organize data from different locations into separate folders or PSTs, and each mailbox exports to a PST named after it.

Can a user export their own mailbox without an admin?

Yes, with Outlook for Windows: File > Open & Export > Import/Export > Export to a file > Outlook Data File (.pst).

Is the eDiscovery Export Tool still needed?

No. Microsoft says the Microsoft Office 365 eDiscovery Export Tool is being retired and packages are downloaded through the browser from Process manager.

Sources

Official sources

Vendors change menus and requirements. Confirm on the source before you rely on a detail. Last checked 4 Nov 2026.

Microsoft Learn: Export search results in eDiscoveryMicrosoft Learn: Limits in eDiscoveryMicrosoft Learn: Assign permissions in eDiscoveryMicrosoft Learn: Create and manage cases in eDiscoveryMicrosoft Learn: Create a search for a case in eDiscoveryMicrosoft Support: Back up your Outlook emailMicrosoft Support: Export emails, contacts, and calendar items to Outlook using a .pst file