What a PST file is and why you need one

A PST file is a container that holds copies of your Outlook emails, contacts, and calendar events on your computer. Think of it as a separate filing cabinet for messages you want to keep separate from your main inbox — either as a backup, or to organize mail by project, client, or year.

PST files are useful when you want to move emails out of your active inbox to free up space, keep a permanent record of important messages before they're deleted, or organize old mail by topic without cluttering your working folders. Unlike leaving everything in Outlook, a PST file stays on your computer even if your email account is deleted or you switch devices.

The process differs slightly depending on whether you use Outlook on Windows or Mac, and whether your email account is through Microsoft 365, a work server, or an older standalone version of Outlook. The steps below cover the most common setup: Outlook on Windows with a Microsoft 365 or Outlook.com account.

Key Takeaways

  • A PST file is a backup copy of your emails stored on your computer, separate from your main Outlook account.
  • You create a PST file by exporting folders from Outlook, not by creating a blank file and importing into it.
  • The export process takes a few minutes and creates a single .pst file you can move, copy, or store on an external drive.
  • Once created, you can open a PST file in Outlook by adding it as a data file, which makes the emails searchable and readable inside Outlook.
  • PST files can become corrupted if Outlook crashes while writing to them, so store backups on a separate drive and keep the original in Outlook.

How to export emails into a new PST file on Windows

Open Outlook and go to the File menu at the top left. Click Open & Export, then select Import/Export. A dialog box will open with a list of actions. Choose Export to a file and click Next.

On the next screen, select Outlook Data File (.pst) from the list and click Next. You will then see your folder list. Click the folder you want to export — for example, Inbox, Sent Items, or a custom folder you created. If you want to export that folder and everything inside it, make sure the checkbox next to it is marked. Click Next.

A file browser will open asking where you want to save the PST file. Choose a location on your computer — your Documents folder or Desktop is easiest to find later. Type a name for the file (for example, "Inbox Backup 2024" or "Client Files") and click Finish. Outlook will process the export, which may take a few minutes if you have thousands of emails. When it finishes, you will see a confirmation message.

How to export emails on Mac

Open Outlook and click Tools in the menu bar at the top. Select Export. A dialog box will appear asking what you want to export. Choose Outlook Data File and click the arrow to continue.

Select the folder or folders you want to include in the PST file. You can hold Ctrl and click multiple folders to select more than one. Click the right arrow to move them to the "Folders to export" list on the right side. Click Continue.

A file browser will open. Choose where to save the file and give it a descriptive name. Click Save. The export will process in the background, and Outlook will notify you when it is complete.

Opening a PST file so you can read the emails inside

Once you have created a PST file, it sits on your computer as a single file — but Outlook does not automatically open it. To read the emails inside, you need to add it to Outlook as a data file.

On Windows, go to File > Open & Export > Open Outlook Data File. A file browser will open. Navigate to where you saved your PST file, click it, and click Open. The PST file will now appear in your folder list on the left side of Outlook, usually at the bottom, with a name like "Outlook Data File" or the name you gave it during export.

On Mac, go to File > Open > Outlook Data File. Find your PST file and click Open. It will appear in your folder list.

Once the PST file is open in Outlook, you can search it, read emails, and move messages in and out of it just like any other folder. The emails are now part of your Outlook workspace.

Where to store your PST file and how to keep it safe

PST files can become corrupted if Outlook crashes while it is writing to the file, or if your computer loses power unexpectedly. For this reason, do not keep your only copy of important emails in a PST file that is actively open in Outlook every day.

Instead, create the PST file as a one-time backup: export your emails, close the PST file in Outlook, and then copy it to an external drive or cloud storage like OneDrive or Google Drive. This way, if something goes wrong with your main Outlook account, you still have a copy of those emails elsewhere.

If you need to access the PST file regularly, keep one copy open in Outlook for daily use, and keep a second backup copy on an external drive that you update every few months. Never rely on a single PST file as your only backup.

Exporting specific date ranges or search results into a PST file

The standard export process exports an entire folder. If you only want emails from a specific time period or matching certain words, you can narrow down what gets exported by creating a temporary folder first.

In Outlook, use the search box at the top to find the emails you want — for example, search for a client name, a date range, or a keyword. Once the search results appear, select all of them (Ctrl+A on Windows, Cmd+A on Mac), right-click, and choose Move > New Folder. Give the folder a temporary name like "Export Temp". Then follow the export steps above, selecting only that temporary folder. Once the export is complete, you can delete the temporary folder.

This method takes a bit longer but gives you a PST file with only the emails you need, rather than an entire year's worth of mail.

Troubleshooting common PST file problems

If Outlook says "Cannot open the Outlook Data File" when you try to open a PST file, the file may be corrupted or in the wrong format. Try creating a new export of the same folder rather than trying to repair the damaged file. If you have a backup copy on an external drive, try opening that instead.

If the PST file opens but appears empty, check that you exported the correct folder. Go back to your original Outlook account and verify that the folder you exported actually contains emails. If it does, try exporting it again to a new PST file with a different name.

If Outlook is running very slowly after you opened a large PST file, close the PST file (right-click it in the folder list and select Close) and remove it from Outlook. Large PST files can slow down Outlook's search and sync functions. Instead, keep the PST file closed and only open it when you need to search or retrieve specific emails from it.

Frequently Asked Questions

Can I email a PST file to someone else so they can read my emails?

Yes, but PST files are large — often 100 MB to several GB — so email is usually not practical. Instead, use file-sharing services like OneDrive, Google Drive, or Dropbox to send the file. The person receiving it will need Outlook installed on their computer to open it. They can then add it to their Outlook the same way you did.

What is the difference between exporting to PST and using Outlook's archive feature?

Outlook's archive feature automatically moves old emails to a separate PST file called archive.pst, which stays open in Outlook. Exporting to PST is manual and gives you control over which emails go into the file and where it is stored. Archive is better for automatic cleanup; export is better for one-time backups or organizing by project.

Can I import emails from a PST file back into my main Outlook inbox?

Yes. Open the PST file in Outlook, select the emails you want to move back, right-click, and choose Move > Inbox (or another folder). The emails will be copied back to your main account. This is useful if you archived something by mistake or need to restore emails after switching computers.

Will creating a PST file delete the emails from my Outlook account?

No. Exporting creates a copy of the emails in the PST file. The originals stay in your Outlook account. If you want to remove them from your inbox after backing them up, you must delete them manually from Outlook after confirming the PST file was created successfully.

Can I create a PST file on a Mac and open it on Windows, or vice versa?

Yes. PST files are the same format on both systems. You can create one on a Mac, move it to a Windows computer, and open it in Outlook for Windows without any conversion. The same is true in reverse.