“Mailbox Full”: Archive Old Email and Free Up Space in Outlook

Here’s what to do when Outlook says your mailbox is full: move old email into an archive file, which frees up space without deleting anything.

Why archive instead of delete?

Keeps everything, just off your mailbox — Archived mail moves to a file on your computer, not the trash
Still right there when you need it — It shows up as a separate mailbox, searchable like any other
Frees up space immediately — Unlike Deleted Items, which still counts until you empty it

How to archive old email and free up space in Outlook

Outlook

1Move old email into an archive file

File → Open & Export → Open Outlook Data File. Browse to the file, and click Open.

WHAT TO DOIt appears as its own mailbox, right in your folder list, safely off your main mailbox.

Outlook mailbox full archive email: Move old email into an archive file

A few tips

Empty Deleted Items too — Items there still count against your mailbox size until you empty the folder
Set up AutoArchive — File → Options → Advanced → AutoArchive Settings does this automatically going forward
Sort by size first — Right-click a column header, sort by size, to find what’s actually taking up room

Recap: fixing a full Outlook mailbox

File, Open & Export, Open Outlook Data File
Browse to the file, click Open
It appears as a separate, searchable mailbox
Empty Deleted Items too, and consider AutoArchive

Printable quick guide

Fix a Full Outlook Mailbox (1-page quick guide PDF)

Frequently asked questions

How do I archive old email in Outlook?

Click File, then Open & Export, then Open Outlook Data File. Browse to where you keep (or want to create) a .pst file, select it, and click Open. It appears as its own mailbox in the folder list.

Does archiving email delete it?

No. Archiving moves it to a file on your own computer; it’s still there, searchable, in a separate mailbox, not deleted.

Does emptying Deleted Items actually free up space?

Yes, and it’s an easy one to forget: items in Deleted Items still count against your mailbox size until you empty that folder.

What is AutoArchive in Outlook?

A setting under File, Options, Advanced, AutoArchive Settings that automatically moves older items to a local archive file on a schedule you choose. It isn’t available in new Outlook for Windows yet.

Archived mail isn’t gone; it moves to a file on your own computer and shows up as a separate, searchable mailbox right in Outlook’s folder list.