A .pst file is a whole Outlook mailbox in one file - every folder, email, attachment, calendar entry and contact. It is what Outlook exports, what an employer hands over when an account is closed, and what sits in a backup from an old PC; an .ost is the copy Outlook keeps of a mailbox that lives on Exchange or Outlook.com. Without Outlook on Windows, neither opens - and Outlook for Mac cannot open an .ost at all. This reads both.
The mailbox is read in place, a slice at a time, rather than loaded into memory, so a file of several gigabytes opens as quickly as a small one. Browse the folders, sort a folder by date, sender, subject or size and filter it by dates, attachments or unread - a folder of tens of thousands lists in a moment - and read each message as it was sent, formatting and pictures included, with remote images held back until you allow them. Emails attached to emails open in place. Save attachments, search subjects, senders, recipients and attachment names across the whole mailbox (the first 500 matches are shown), and export a message as .eml or Outlook .msg, a folder as .mbox, a ZIP or a CSV list for a spreadsheet, the whole mailbox as a ZIP, contacts as vCard or CSV, calendars as iCalendar and tasks as CSV, for Thunderbird, Apple Mail, Google, iCloud, Excel or an archive. Look for deleted items finds messages still in the file that no folder lists any more. It is a web page, not a program to install, so it works the same on Windows, a Mac, a Chromebook or Linux.
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- How do I open a PST file on a Mac?
- Open it here in Safari or Chrome - nothing to install. Outlook for Mac can import a PST but cannot simply open one to read, and cannot use an .ost at all. To move the mail into Apple Mail, save each folder as .mbox and use File, Import Mailboxes.
- Can I convert PST to MBOX or EML?
- Yes. The .mbox button saves every message in the open folder as one mailbox file that Thunderbird, Apple Mail and most mail tools import, and .eml saves the message you are reading as a standard email file, attachments included. ZIP saves the folder and the folders inside it with every email as its own .eml file, and Export all does the same for the whole mailbox, keeping Outlook's folder tree - with contacts as .vcf and .csv and calendars as .ics alongside.
- Can I convert PST to MSG?
- Yes. The .msg button beside .eml saves the message you are reading as an Outlook message file, with its attachments and any emails attached to it inside. The .msg ZIP button above a folder saves the folder and the folders inside it with every email as a .msg file, and Save list does the same for just the messages listed - a filtered list or search results. Outlook opens .msg files, and so does the MSG Viewer here.
- Can it recover deleted emails from a PST file?
- Sometimes. Look for deleted items, under the folders, reads the whole file for messages that are still in it but that no folder lists: items deleted from Deleted Items whose space Outlook has not reused yet, and items cut off from their folder. They appear in Recovered items, to read and save like any other, each saying how it was found and what of it is missing. What has been overwritten cannot come back: Outlook reuses the space of deleted items as new mail arrives, and compacting the file clears it, so work from a copy made as soon as possible after the deletion. Old copies of messages still in the mailbox are left out.
- Can I sort or filter the messages in a folder?
- Yes. A folder opens newest first; above the list, choose Date, From, Subject or Size and press the arrow to reverse the order. Filter narrows it to a range of dates, messages with attachments, or unread ones, and shows how many match. The same works on search results, and Save list prints or saves exactly what is listed.
- How do I get my contacts and calendar out of a PST?
- Open the Contacts folder and press .vcf for a vCard file that iPhones, Android, Google Contacts, iCloud and Outlook import, or .csv for Outlook's contact spreadsheet layout. Open the Calendar and press .ics, which Google Calendar, Apple Calendar and Outlook import. Repeating meetings stay repeating, in the time zone they were set up in, with occurrences that were deleted left out; a single occurrence that was moved or edited comes out at its usual series time.
- Can I save all the attachments at once?
- Yes. Attachments, above the message list, saves every attachment in the folder and the folders inside it as a ZIP (split into parts if it is very large). Files with the same name are numbered rather than overwritten.
- How big a PST file can it open?
- No set limit. The file is read in place, a slice at a time, instead of being loaded into memory, so a mailbox of many gigabytes opens without filling the computer’s memory. Exporting a very large folder as .mbox does build that file in memory, so a folder of many thousands of messages is best exported on a computer rather than a phone. The ZIP exports are written as they go: in Chrome and Edge straight into a folder you choose, so even the whole of a large mailbox does not have to fit in memory. A ZIP that would pass 3.5 GB or 60,000 files carries on in a second file, "(part 2)", and so on, as a single ZIP stops working past 4 GB; other browsers download it in parts of about 500 MB.
- Can I view a PST file online without uploading it?
- Yes - that is how this page works. It runs in the browser tab: the file is read from your disk by your own computer and never sent anywhere, which matters for a mailbox full of private mail.
- Is there a PST viewer for Chromebook or Linux?
- This one: Outlook and most free PST viewers are Windows programs, but this is a web page, so it opens PST and OST files on a Chromebook, on Linux, on a Mac or on Windows alike. On a Chromebook, copy the file into Downloads or a USB stick and drop it onto the page from the Files app.
- Can it open a PST file that has a password?
- Yes, it opens PST files that have an Outlook password. PST files saved with Outlook's High encryption setting are not supported.
- Can I export a PST folder to Excel?
- Yes. The .csv button above a mail folder saves its messages as a spreadsheet list - date, sender and address, To, Cc, subject, attachment names, size and read or unread - which Excel, Numbers and Google Sheets open. Contacts and tasks have their own .csv buttons, and Export all includes them.
- What if my PST file is damaged and will not open?
- Try PST Repair: it reads a damaged .pst or .ost without trusting its index, says what is broken, and copies everything it can still read into a new PST, which then opens here and in Outlook.
- What is the difference between a PST and an OST file?
- A PST is a standalone mailbox file - exported, archived or used by a POP account. An OST is the local copy Outlook keeps of a mailbox that lives on a server, such as Exchange, Microsoft 365 or Outlook.com. Both hold the same kind of content, and both open here. To turn an OST's mail into a PST that any Outlook opens, use the OST to PST Converter.