How to open a PST file on a Mac without Outlook
Short answer
Install OldMail from the Mac App Store, press ⌘O and pick your .pst file. It opens as a mailbox — folder tree on the left, message list in the middle, the selected message on the right — with attachments intact. There is no Outlook involved, no conversion step, and the file never leaves your Mac.
If you would rather not install anything, the alternatives are further down: importing into Outlook for Mac, borrowing a Windows PC, or an online converter (which we would avoid — see why below).
What is a PST file?
A .pst file — an Outlook Data File — is how Microsoft Outlook on Windows stores mail on disk. One file can hold an entire mailbox: the folder structure, every message, the attachments, calendar items and contacts. People usually end up with one after archiving old mail, leaving a job, or exporting a mailbox before a migration.
It is a proprietary Microsoft format, and that is the whole problem. A PST is not a folder of emails you can browse; it is a single binary database. Renaming it, unzipping it or opening it in a text editor gets you nowhere.
There are two generations of the format. Modern files (Outlook 2003 and later) are Unicode PSTs and can be several gigabytes. Very old files from Outlook 2002 and earlier are ANSI PSTs, capped at 2 GB — worth knowing, because most tools, OldMail included, only handle the modern kind.
Why macOS cannot open it out of the box
macOS has no built-in support for Outlook's data formats. Double-clicking a .pst either does nothing or hands it to an app that cannot read it. Apple Mail can import mailboxes, but the formats it understands are mbox and its own, not PST.
So you need something that can read the format directly — or a way to get the mail out of it first.
Open a PST file on your Mac in four steps
-
Install OldMail
Get it free from the Mac App Store. It needs macOS 13 or later and is about 1.5 MB, so it downloads in seconds.
-
Open the file
Press ⌘O and select your
.pst, or just drag the file onto the OldMail window. You can also right-click the file in Finder and choose Open With. -
Wait a moment for the index
Messages appear in the list as they are read rather than after the whole file is processed, so even a several-gigabyte archive starts filling within about a second. A small strip shows the count while it works.
-
Read, search, export
Click through the folder tree, use the search box to filter by sender or subject, and open attachments as usual. Press ⇧⌘E to save the message you are reading as a PDF or Word document, or use the download button to pull it out as a standard
.emlfile.
Everything happens on your Mac: no account, no sign-in, and no copy of your mailbox sent to a server.
Other ways to do it
OldMail is not the only route, and depending on what you have available another one may suit you better.
Import it into Outlook for Mac
If you already have a Microsoft 365 subscription, some versions of Outlook for Mac can import a PST from File → Import. Support has come and gone between releases, so check your version — and be aware that importing copies everything into your live mailbox, which is not what you want if you only need to read one old message.
Use a Windows PC
Outlook on Windows opens PST files natively: File → Open & Export → Open Outlook Data File. Perfectly reliable if you have a Windows machine to hand, and completely useless if you do not.
Online PST converters
Plenty of sites offer to convert a PST for you. Think carefully before using one: you would be uploading an entire mailbox — years of correspondence, attachments, possibly client or medical information — to a third-party server you know nothing about. For anything work-related this is usually a data-protection problem, not just a preference.
Common problems
"The file is not supported"
The most common cause is an ANSI-format PST from Outlook 2002 or earlier. These use an older layout that OldMail does not read. Opening the file once in a modern Outlook on Windows and re-exporting it produces a Unicode PST that works.
The archive is enormous
Multi-gigabyte PSTs are normal and fine. Because the message list is built from message headers only, opening a large archive is fast and does not load every attachment into memory.
I only need one message out of it
Select it and use the download button to save it as an .eml, which almost every mail client can open — or export it straight to PDF with ⇧⌘E.
Open it in about a minute
OldMail is free on the Mac App Store. It reads PST files — and OST, MSG, EML, EMLX and MBOX — without Outlook and without uploading anything.
Frequently asked questions
Can I open a PST file on a Mac without installing Outlook?
Yes. OldMail reads Outlook Data Files directly on macOS with its own parser, so nothing from Microsoft has to be installed and the file is not converted first. Open it with ⌘O or by dragging it onto the window.
Do I have to convert the PST file first?
No. Conversion tools exist, but they are a workaround for software that cannot read the format. OldMail parses the PST as it is, which means nothing is duplicated on disk and nothing is uploaded anywhere.
Is it safe to open a work PST this way?
The file is read locally on your Mac. OldMail has no account, no sign-in and no server, and does not send message content anywhere. That is a meaningful difference from web-based converters, which require you to upload the whole mailbox.
What if my PST is password protected?
Outlook's password protection is applied by Outlook itself rather than by encrypting the file's contents, and behaviour varies by how the file was produced. If a file will not open, the reliable route is to remove the password in Outlook on Windows and export it again.
Can I open an OST file the same way?
Yes — the process is identical. There is a separate guide for OST files, which are the offline copies Outlook keeps of an Exchange or Microsoft 365 mailbox.