Backing up Outlook matters for a few real reasons: account loss or lockout, device swaps, retention policies that auto-delete old mail, and legal or compliance holds. The right method depends on which version of Outlook you’re running, what kind of account you have, and whether you have admin access.

Here’s how to back up Outlook mail in every version, plus how to restore it.

---

1. Classic Outlook for Windows — Export to PST

Classic Outlook’s Import/Export wizard is still the most reliable way to create a portable, self-contained backup. It produces a .pst (Personal Storage Table) file you can store anywhere, move between machines, and import back into Outlook later.

Run the export

1. Open classic Outlook and click File in the top-left.
2. Click Open & Export > Import/Export.
3. Select Export to a file and click Next.
4. Select Outlook Data File (.pst) and click Next.
5. Select the mailbox or folder you want to back up. To back up everything, click the account name at the top.
6. Tick Include subfolders, then click Next.
7. Click Browse to choose a save location (pick a folder outside your OneDrive or Documents if you want a clean backup target).
8. Choose how to handle duplicates:
   • Replace duplicates with items exported
   • Allow duplicate items to be created
   • Do not export duplicate items
9. Click Finish.

Add a password (optional)

When you click Finish, Outlook shows the Create Outlook Data File dialog. Enter a password in both fields and click OK to encrypt the .pst. Leave it blank to skip encryption.

Note on size: PST files are capped at 50 GB in modern Outlook. Large mailboxes may take an hour or more to export — leave Outlook open and connected until the dialog closes on its own.

---

2. What’s Inside a PST vs an OST File

These two file formats show up constantly in Outlook, and they are not interchangeable.

File	What it is	Portable?	Used for backup?
.pst (Personal Storage Table)	Standalone data file containing mail, calendar, contacts, tasks	Yes — any machine with Outlook can open it	Yes
.ost (Offline Storage Table)	Local cached mirror of your Exchange or Microsoft 365 mailbox	No — tied to the account and profile that created it	No

The .ost file lives at C:\Users\<you>\AppData\Local\Microsoft\Outlook\ and gets rebuilt any time Outlook re-syncs. Copying it to another machine won’t work. If you want a portable backup, you need to export a PST — the OST is not a substitute.

---

3. New Outlook for Windows — Native PST Export (GA July 2025)

The new Outlook for Windows shipped native PST export to general availability in July 2025. You no longer need to fall back to classic Outlook just to produce a backup.

Run the export

1. Open new Outlook for Windows.
2. Click the Settings gear (top-right), go to General > Storage (or Accounts > Your accounts depending on build).
3. Click Export mailbox (or Export to PST file in some builds).
4. Pick the account you want to back up.
5. Choose which item types to include — mail is fully supported; calendar and contacts export as read-only inside the PST.
6. Pick a save location and click Export.
7. New Outlook writes a .pst file you can store, move, or open in classic Outlook.

Limitations to be aware of

• Import from PST is not yet supported in new Outlook. To restore a backup, add the account to classic Outlook for Windows and use the import wizard in section 7.
• Calendar and contacts are read-only in the exported PST — you can open them in classic Outlook and copy individual items, but you can’t bulk-restore them on top of a mailbox from new Outlook.
• Password-protected PSTs are not yet available from new Outlook’s export — if you need encryption on the file itself, export from classic Outlook instead, or store the PST inside an encrypted container (BitLocker, VeraCrypt).

Fallback: open the account in classic Outlook

If your build doesn’t yet show the Export mailbox option, or you need password-protected PSTs:

1. Install or reopen classic Outlook for Windows.
2. Add the same Microsoft 365 or Outlook.com account (File > Add Account).
3. Wait for the mailbox to sync.
4. Follow the Import/Export steps in section 1.

---

4. Outlook on the Web — IMAP & eDiscovery

Outlook on the web (outlook.office.com or outlook.live.com) has no native backup or export button. You have two real options.

Connect via IMAP and back up locally

1. Enable IMAP for your account (for Microsoft 365, this is usually on by default; for Outlook.com, check Settings > Mail > Sync email).
2. Add the account to classic Outlook for Windows, Outlook for Mac, Thunderbird, or eM Client using IMAP.
3. Let the client download the full mailbox.
4. Export a PST (classic Outlook), OLM (Mac), or the client’s native format.

IMAP will pull mail and most folders, but not contacts, calendar, or tasks — back those up separately via Outlook.com export or the People/Calendar export options.

Admin Content Search

Same as section 6 — if the mailbox is on Microsoft 365 Business or Enterprise, an admin can export it to PST via Purview.

---

5. Outlook for Mac — Export to OLM

Outlook for Mac doesn’t support .pst. Instead, it uses .olm (Outlook for Mac Data File).

1. Open Outlook for Mac.
2. Click File > Export (on newer builds, this may be Tools > Export).
3. Tick the item types you want to back up: Mail, Calendar, Contacts, Tasks, Notes.
4. Optionally filter by category or date range (useful for partial backups).
5. Click Continue.
6. Choose a save location for the .olm file and click Save.
7. Outlook writes the archive and shows Export Complete when done.

Restore from OLM

1. Go to File > Import.
2. Select Outlook for Mac Data File (.olm).
3. Browse to your .olm file and click Import.
4. Imported items land in a folder labeled On My Computer > Imported.

Cross-platform note: OLM and PST are not directly compatible. To move a Mac backup to Windows, you’ll need a conversion tool (Stellar, SysTools, Kernel) or you can re-sync the account on a Windows machine and export a fresh PST from there.

---

6. Admin: Export PSTs from Microsoft Purview (Content Search)

For Microsoft 365 Business and Enterprise, admins can export any user’s mailbox to PST without touching the user’s client. This is the method used for legal holds, offboarding, and large-scale backups.

1. Sign in to the Microsoft Purview compliance portal with an account that has the eDiscovery Manager or Compliance Administrator role.
2. Go to Solutions > eDiscovery > Content search.
3. Click + New search.
4. Name the search and add a description.
5. Under Locations, toggle Exchange mailboxes on and pick the users or groups to include.
6. Add keywords, date ranges, or other filters (optional — leave blank to export everything).
7. Click Save & run.
8. When the search finishes, open it and click Actions > Export results.
9. Choose export options (include unindexed items, deduplicate, etc.) and click Export.
10. On the Exports tab, wait for the job to finish, then click the export name.
11. Copy the export key, click Download results, and open the Microsoft Office 365 eDiscovery Export Tool when prompted.
12. Paste the export key, pick a save location, and click Start. Mail is delivered as one or more PST files.

The eDiscovery Export Tool only runs on Windows and requires Microsoft Edge or ClickOnce-enabled browser support.

---

Encrypt Your Backup with a Password

The PST export wizard lets you set a password in the final Create Outlook Data File dialog. Enter it twice and click OK. To change or remove the password later:

1. In Outlook, go to File > Account Settings > Account Settings > Data Files.
2. Select the PST, click Settings, then Change Password.

Be aware: PST password encryption is weak by modern standards — it’s more of a deterrent than real protection. For sensitive backups, store the .pst inside an encrypted container (BitLocker, FileVault, VeraCrypt, 7-Zip AES-256 archive) or on an encrypted drive rather than relying on Outlook’s built-in password alone.

---

Import a Backup Back into Outlook

1. In classic Outlook, click File > Open & Export > Import/Export.
2. Select Import from another program or file and click Next.
3. Select Outlook Data File (.pst) and click Next.
4. Click Browse and pick your backup file.
5. If the PST is password-protected, enter the password.
6. Choose how to handle duplicates:
   • Replace duplicates with items imported
   • Allow duplicates to be created
   • Do not import duplicates
7. Click Next.
8. Pick the folder to import from (usually the top-level account) and tick Include subfolders.
9. Choose whether to import into the same folder in your current mailbox or a specific folder.
10. Click Finish.

You can also open a PST as a secondary data file without importing: File > Open & Export > Open Outlook Data File > browse to the .pst. It appears as a separate folder tree in the sidebar.

---

How Often Should You Back Up?

There’s no universal answer, but a reasonable baseline:

• Monthly manual PST export for personal accounts — covers device loss, account lockout, and accidental deletion.
• Weekly or nightly for accounts where losing a week of mail would hurt (freelancers, consultants, anyone invoicing through email).
• Continuous via MailStore Home or a similar archiving tool if you want no gaps — it syncs incrementally in the background.
• Before any migration: version upgrades, new machine setup, mailbox moves between tenants, leaving a job.

Automating exports on classic Outlook is possible through PowerShell with the New-MailboxExportRequest cmdlet (on-premises Exchange only) or a scheduled script that launches Outlook with the /importprf switch, but most users are better served by a tool like MailStore.

---

Quick Reference

Version	Native export?	Format	Password support
Classic Outlook for Windows	Yes — Import/Export wizard	.pst	Yes (weak)
New Outlook for Windows	Yes — Export mailbox (GA July 2025)	.pst (export only; calendar/contacts read-only)	No
Outlook for Mac	Yes — File > Export	.olm	No
Outlook on the web	No	—	—
Microsoft 365 Admin (Purview)	Yes — Content Search	.pst	Via export tool

---

Which Method Should You Use?

• Classic Outlook for Windows user? Run the Import/Export wizard to produce a .pst. This is the most complete, most portable backup available.
• New Outlook for Windows user? Use the built-in Export mailbox command for a .pst (mail fully supported, calendar/contacts read-only). Fall back to classic Outlook only if you need password-protected PSTs or your build doesn’t show the export option yet.
• Outlook on the web only? Connect the mailbox to a desktop client via IMAP, let it sync, then back up the local copy.
• Mac user? Use File > Export for an .olm archive.
• IT admin? Purview Content Search produces PSTs at scale without touching user devices — best for compliance, legal holds, and offboarding.
• Want something that runs automatically? MailStore Home (free for personal use) archives continuously and can produce PSTs on demand.

---

Automate More of Your Email Work

Backups are the insurance policy — but most of the email work you do every day (sorting, replying, scheduling, following up) doesn’t need a backup, it needs an assistant. Carly is an AI assistant that connects to Outlook and 200+ other apps and handles the repetitive inbox work for you.

More on Outlook: How to export emails from Outlook · How to archive emails in Outlook · How to recover deleted emails in Outlook · How to create folders in Outlook · How to import contacts into Outlook · How to fix Outlook search not working · How to create a shared mailbox in Outlook · How to create an email template in Outlook

Related Articles

Guides

How to Export Emails from Outlook (Every Method, 2026)

Apr 3, 2026

Guides

How to Save an Email as PDF in Outlook (2026 Guide)

Apr 15, 2026

Guides

How to Mark an Email as Unread in Outlook (2026 Guide)

Apr 15, 2026