archive.pst is the Outlook data file that classic Outlook’s AutoArchive creates to hold older items it moves out of your mailbox, so it often contains years of email that exist nowhere else. You can delete it, but anything in it is then gone for good, so open it and check what it holds first. PstVault opens archive.pst on Windows without Outlook, read-only, so you can search it and export the messages you want to keep before you decide.
This guide explains where the file comes from, what is likely inside it, and how to decide whether to keep it.
Open archive.pst without Outlook and see what is in it before you delete anything.
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Where does archive.pst come from?
Microsoft’s page on AutoArchive settings explains it. AutoArchive is a feature of classic Outlook for Windows that moves items past a certain age out of your mailbox into an archive file. The archive file is created automatically the first time AutoArchive runs, at this location by default:
C:\Users\YourUserName\Documents\Outlook Files\archive.pstMicrosoft notes that some of these folders may be hidden. If you do not remember turning AutoArchive on, it may have been set up on an earlier computer, by a prompt you accepted, or by your workplace IT.
AutoArchive is not available in the new Outlook for Windows, so if you moved to new Outlook, your old archive.pst may still be sitting in that folder, unused.
What is inside archive.pst?
Whatever AutoArchive moved. Microsoft lists the default aging periods:
| Folder | Default age before archiving |
|---|---|
| Inbox and Drafts | 6 months |
| Sent Items and Deleted Items | 2 months |
| Outbox | 3 months |
| Calendar, Tasks, Notes and Journal | 6 months |
| Contacts | Not archived by default |
Those are defaults; your settings may differ. The important point is that archived items are moved, not copied. They are taken out of your mailbox and put in the file, which is why archive.pst often holds the only copy of older mail, sent items and calendar entries.
Microsoft also notes that items in the archive can only be deleted manually. AutoArchive does not clear the archive out for you, so the file tends to grow for as long as AutoArchive runs.
Did AutoArchive delete anything instead of archiving it?
It can. Microsoft’s page explains that AutoArchive has two ways of dealing with old items: move them to the archive file, or permanently delete items that have passed their aging period. If an account or folder was set to delete, those items were not archived, and they will not be in archive.pst.
So if you open the archive and a folder you expected is missing or thin, check the AutoArchive settings for that folder. In classic Outlook, each folder can have its own settings on the AutoArchive tab of its Properties. That will not bring deleted items back, but it explains what you are looking at and tells you what to change if you keep using AutoArchive.
Can you delete archive.pst?
Technically, yes. It is a file like any other, and deleting it does not break Outlook. But before you do, consider:
- It may be the only copy. Archived items were moved off the mail server. Deleting the file deletes those items.
- It may matter later. Old invoices, contracts, receipts and correspondence are easy to need years after you thought you were done with them.
- Your workplace may have rules. On a work computer, ask IT before deleting any mail archive; there may be retention requirements.
- Outlook may have it open. If archive.pst is listed in classic Outlook’s folder pane, close Outlook first, or remove the file from Outlook before moving it.
A sensible order is: look inside, export what you want to keep in a format you can read without Outlook, keep a backup copy of the PST on another drive, and only then delete the original if you still want to.
How do you open archive.pst to check it?
In classic Outlook, Microsoft’s page gives the route: click the File tab, then on the Open tab click Open Outlook Data File, and choose the archive. There is also a setting to show the archive folder in the folder list alongside your other folders.
In new Outlook, support for PST files is different; see our guide on opening a PST in new Outlook.
Without Outlook, use a PST viewer. PstVault opens Outlook data files so you can search the archive and export the messages you choose, without installing Outlook, connecting to a mailbox or uploading your email. It opens the PST read-only and creates new output files without overwriting existing ones, so the archive stays unchanged while you look.
Search archive.pst by sender, subject, words or date, without Outlook.
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What should you export before deleting?
With PstVault you can browse folders and narrow your selection by sender, recipient, subject, words in the message body or date, check messages in a text preview, then export:
| What you want to keep | Export as |
|---|---|
| Important conversations for reading or printing | PDF, individual files or one bookmarked PDF |
| Messages to reopen in an email program later | EML, with available attachments |
| Offline reading copies with inline pictures | HTML |
| Contacts | CSV table or vCard files |
| Calendar entries | ICS files |
| Attachments on their own | Original files |
An export report identifies complete, partial, failed and unprocessed items, so you can check what needs attention before you rely on the export. Mail processing happens on your PC, and PstVault does not upload your email or connect to a mail server.
Our guide on how to export emails from a PST file goes into the formats in more detail, and EML vs PDF vs HTML helps you choose.
What are the limits?
PstVault is designed for readable Unicode PST files, one archive at a time. It does not open OST files, repair damaged archives or decrypt encrypted messages. PDF and HTML exports are reading copies, and formatting may differ from the original. If your archive.pst is very old, check it opens; if it does not, see PST is not an Outlook data file.
What if you find several archive files?
Some people find archive.pst alongside archive1.pst, or copies on an old drive. Each one is a separate file and may cover a different period. Check each before deleting any of them. If you are hunting for old files on a previous computer’s drive, see finding old Outlook PST files on an old hard drive.
Frequently asked questions
Will deleting archive.pst free up space in my mailbox?
No. The items in it were already moved out of your mailbox. Deleting the file frees disk space on your PC only.
Is archive.pst the same as a backup?
No. It holds items that were moved, not copied, so it is often the only copy of them.
Can I stop Outlook creating archive.pst?
In classic Outlook, clear the Run AutoArchive every n days check box in the AutoArchive settings. Microsoft’s AutoArchive page explains the other options, including a prompt before each run.
Can PstVault change or damage my archive?
No. It opens the PST read-only and writes only new output files.
Try PstVault
PstVault is a one-time purchase with a free trial in the Microsoft Store; the listing shows the current price and system requirements. Open a copy of your archive.pst and search it for the oldest mail you might still need. More detail is on the PstVault product page, and our guide on what a PST file is covers the format.
Keep what matters from an old archive in files anyone can open.
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Last updated 24 October 2026. Published by Automata Labs, a software company in Canada.