Glossary

What Is a PST File?

A PST file is Outlook's Personal Storage Table, a single database file that keeps your emails, contacts, calendar entries, and tasks on your own computer. Outlook creates it to store a mailbox locally, separate from any mail server. A modern PST can grow to as much as 50 GB, which is why large mailboxes are usually split or archived.

TL;DR

PST is Outlook's local mailbox file. Convert it to PDF to open and read the messages without Outlook.

50 GB
the maximum size a modern Unicode PST file can reach in Outlook 2010 and later

What a PST File Stores

A PST is not just mail. Outlook packs the whole personal mailbox into one file:
  • Email messages, with their folders and read or unread state.
  • Contacts, calendar appointments, tasks, and notes.
  • Rules, signatures, and other account settings tied to the data file.
Because everything lives in one place, copying a single PST moves a person's entire Outlook history to a new machine.

Why PST Files Grow and Break

The single-file design is also the weakness. Older ANSI PST files from Outlook 2002 and earlier were capped near 2 GB and would corrupt once they hit that wall. Unicode PST files lifted the limit, but a file that swells past tens of gigabytes still slows Outlook and risks damage if the program closes mid-write.

Never copy a PST while Outlook is open. The file is locked and a half-written copy can come back corrupt. Close Outlook first, then move the file.

How to Open a PST Without Outlook

You do not always have Outlook on the PC holding the file. The reliable route is a converter that reads the PST directly and turns the messages into PDF documents you can open and search anywhere.

What you'll need
  • PST to PDF Converter: opens a PST and converts its messages to PDF on Windows, no Outlook needed
  • A Windows PC, version 10 or 11
  • The PST file you want to read

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