One of the most popular email clients for personal and professional communication is Microsoft Outlook. If you are using Outlook as an individual or are a part of an organisation, a significant volume of your mailbox data has likely been stored locally by Outlook in a very specific file format, i.e. a PST file. Many users often raise inquiries about what exactly an Outlook PST file contains, as well as what function a PST file serves in Outlook. In this post, we will break down the topic for you in simple language and also present the methods of accessing PST files without Outlook or macOS.

What Is a PST File in Outlook?

Simply put, a PST or Personal Storage Table is a data file that is used locally by Microsoft Outlook to save copies of emails and other items from the mailbox. You could say that the PST file is your personal archive, keeping your Outlook data safe and accessible even when offline.

Basically, PST files are for POP3, IMAP and standalone Outlook profiles, where they serve as storage, backup, and transfer points of mailbox data.

What Does an Outlook PST File Contain?

An Outlook PST file contains much more than just emails. It is a complete container of Outlook mailbox data. Below are the key items stored in a PST file:

1. Emails and Email Folders

All sent, received, and draft emails are stored inside the PST file. This includes:

• Inbox emails
• Sent Items
• Drafts
• Deleted Items
• Custom user-created folders

Each email retains its attachments, formatting, metadata, and timestamps.

2. Attachments

Any files attached to emails—such as PDFs, images, documents, or spreadsheets—are stored within the PST file along with the email message.

3. Contacts

PST files store your Outlook Contacts, including:

• Names
• Email addresses
• Phone numbers
• Company details
• Notes

This makes PST files useful when migrating or backing up address books.

4. Calendar Items

All calendar-related data is stored in the PST file, such as:

• Meetings
• Appointments
• Events
• Recurring schedules

This ensures continuity when moving Outlook data between systems.

5. Tasks and To-Do Lists

Outlook tasks, reminders, and to-do lists are also saved inside the PST file, making it a complete productivity data store.

6. Notes and Journals

Sticky notes and journal entries created in Outlook are preserved in PST files, which can be useful for historical reference or data recovery.

What Is the Use of a PST File in Outlook?

The PST file serves several important purposes in Outlook. Let’s look at the main uses.

1. Local Data Storage

One of the primary uses of a PST file is offline access. Even without an internet connection, users can access emails and other Outlook items stored in the PST file.

2. Email Backup and Archiving

PST files are commonly used to:

• Archive old emails
• Reduce mailbox size
• Create backups for future reference

Organisations often store historical emails in PST files for compliance or legal purposes.

3. Data Migration and Transfer

PST files make it easy to:

• Move Outlook data to a new computer
• Migrate user profiles
• Transfer mailbox content between Outlook accounts

Simply importing the PST file restores all data.

4. Recovery from Data Loss

If Outlook crashes or a mailbox becomes inaccessible, PST files act as a recovery source to retrieve important emails and contacts.

5. Centralised Data Management

For users managing multiple accounts, PST files help consolidate data into one manageable file, improving organisation and accessibility.

Challenges with PST Files

Despite their usefulness, PST files also have some limitations:

• PST files require Outlook to open them
• Large PST files can become corrupted
• macOS users cannot open PST files natively
• PST files are not easily readable without special tools

This is where third-party PST viewer tools become helpful.

How to Open and View PST Files Without Outlook or macOS?

If you don’t have Outlook installed or you are using a non-Mac system, accessing PST files can be difficult. To solve this problem, users can rely on dedicated PST viewer tools.

PST Viewer is a reliable tool that allows users to open and read PST files without installing Outlook. It supports viewing:

• Emails with attachments
• Contacts and calendars
• Folder structure in original format

This tool is especially useful for users who only want to view PST data without modifying it.

Open PST File Without Mac

If you’re looking for more flexibility, you can also refer to this detailed guide on opening a PST file without a Mac, which explains different ways to access PST files across platforms without depending on macOS or Outlook. This is helpful for users working on Windows, Linux, or shared systems.

Conclusion

Understanding the in-depth contents of an Outlook PST file and its role in Outlook will lead to more effective management of one's email data. Making a PST file is like putting away your emails, contacts, calendars, tasks, and attachments in one box. Therefore, it is a complete Outlook data archive. The significance of PST files is multifold; they are involved in backup, migration, offline access, and recovery. Nonetheless, if Outlook or macOS is not available, a solution such as installing and using MacUncle PST Viewer can be very helpful and comfortable, requiring minimal effort to open a PST file on a Mac.