Online Archive Mailbox

Each user can have an Online Archive mailbox in Exchange Online—cloud‑hosted, separate from the primary mailbox, visible in Outlook and Outlook on the web.

Licensing Requirements

Requires Exchange Online Plan 2 or Microsoft 365 E3/E5. Verify the correct licenses are assigned before enabling archiving.

Retention Policies

Use retention tags and policies to automatically move messages to the Online Archive after a defined age (e.g., 2 years).

Enable Archive Mailbox

1. Open Exchange admin center.
2. Go to Recipients → Mailboxes.
3. Select the user → Mailbox features → Archive → Enable.

Accessing Archive

Appears in Outlook (desktop) under “Online Archive” and in Outlook on the web under Folders → In‑Place Archive.

Compliance & eDiscovery

Archive content is fully searchable with eDiscovery and supports audit for regulatory compliance.

What Is Local Archive?

Outlook can move older items into a local PST file stored on the user’s device (AutoArchive or manual moves).

Storage & Backup

PSTs reside on local or network storage. Ensure backups and avoid very large PSTs to reduce corruption risk.

AutoArchive

Configure AutoArchive to periodically move older items to PST. Users can choose age thresholds per folder.

Manual Moves

Users can create a PST, then drag and drop messages or folders to the PST for local archiving.

Limitations

• Local PSTs aren’t visible in Outlook on the web.
• Not centrally managed or indexed in eDiscovery.
• Risk if device fails or PST grows too large.

When to Use Local Archive

Best for personal archiving or small mailboxes when cloud archive isn’t licensed. For compliance, prefer Microsoft 365 archiving.

Enable Microsoft 365 Online Archive

1. Confirm user has Exchange Online Plan 2 or M365 E3/E5.
2. Open Exchange admin center → Recipients → Mailboxes.
3. Select the mailbox → Mailbox features.
4. Find Archive and click Enable.
5. Wait for provisioning; verify the “Online Archive” appears in Outlook.

Create Retention to Move to Archive

1. In Microsoft 365, open Compliance or Exchange admin policy area.
2. Create retention tags (e.g., “Move to Archive after 2 years”).
3. Combine tags into a retention policy.
4. Assign the policy to target mailboxes.
5. Allow time for policy to apply; verify items start moving as they age.

Configure Outlook Local Archive (PST)

1. Create PST: File → Account Settings → Data Files → Add (choose a safe folder).
2. AutoArchive: File → Options → Advanced → AutoArchive Settings.
3. Set frequency (e.g., every 14 days), age thresholds, and destination PST.
4. Per‑folder overrides: right‑click folder → Properties → AutoArchive.
5. Manual: drag messages/folders into the PST. Ensure routine backups.