Finding and exporting your Outlook data

What it holds

Outlook and Exchange hold email messages, attachments, folders, calendar appointments and contacts. Shared mailboxes and online archives can contain additional records beyond each employee’s primary mailbox.

Where Outlook shows the size

1. Sign in to the Microsoft 365 admin center as an Exchange Administrator, Reports Reader or Global Administrator.
2. Go to Reports, Usage, choose Exchange, then open Mailbox usage from the Email activity view.
3. Export the CSV, which covers user and shared mailboxes. Total Storage used (MB) and divide by 1,024.
4. Archive mailboxes aren't in the report. Filter on Has Archive and check each one in Exchange Online PowerShell with Get-EXOMailboxStatistics -Archive.
5. For people who have left, list inactive mailboxes in Microsoft Purview under Data Lifecycle Management, or with Get-Mailbox -InactiveMailboxOnly.
6. To check a single mailbox, open it in the Exchange admin center and read Mailbox Usage.

Plan and admin role. Any Microsoft 365 plan with Exchange Online. Reports need Global Administrator, Exchange Administrator or Reports Reader. Names stay hidden until a Global Administrator turns off concealment.

Exporting the full history

1. Add the exporter to the eDiscovery Manager role group in Microsoft Purview; only that group holds the Export role.
2. Under eDiscovery, Cases, create a case and a search over the mailboxes you want, or everyone.
3. Run the search and export it, including departed users so inactive mailboxes are collected.
4. Choose PST for messages and one PST per mailbox. Primary and archive content merge into the same file.
5. Download the packages from Process manager within 14 days. Unzip with 7-Zip rather than the built-in Windows tool.
6. For a single mailbox, classic Outlook for Windows can export to a .pst file with subfolders included.

eDiscovery exports need an E3 or E5 licence on the exporting account.

PSTs can be capped at 1–10 GB and ZIPs at 2–40 GB. Exports over seven days are cancelled, so split large tenants.

A mailbox only becomes inactive if a retention policy or hold was in place before the user was deleted. Otherwise it is gone after 30 days.

New Outlook for Windows can export mail, but calendar and contacts don't come across in its PST files.

You don't need to run an export to talk to us, and there's no need to clean it first — removing personal data is part of our work.