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How to Backup and Restore Your Outlook Data (PST & OST Files)

Step-by-step guide to backup and restore Outlook PST/OST files manually or automatically. Includes free methods, professional tools, and best practices.

Nilesh Kumar Singh

Last edited 64 days ago by Nilesh Kumar Singh.

Emails, contacts, and calendar entries are the lifeblood of modern communication. In Outlook, this critical data is stored in two key file formats: PST (Personal Storage Table) for local accounts and OST (Offline Storage Table) for Exchange/Office 365 accounts.

Imagine losing years of important emails because of a system crash or accidental deletion. That's why backing up Outlook data is non-negotiable. Whether you're migrating to a new computer, recovering from corruption, or simply being proactive, having a backup ensures business continuity.

This guide covers three reliable methods:

Manual export

Automated backups

Third-party tools

Why You Need to Backup Outlook Data

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The Risks of Not Backing Up

Data loss: Hardware failures, malware, or accidental deletion can wipe out years of emails

Corruption: PST files over 50GB become unstable and may refuse to open

Migration headaches: Without backups, switching devices becomes a nightmare

When Backups Save the Day

Upgrading Outlook versions

Transitioning to a new computer

Recovering after system crashes

Preparing for Office 365 subscription changes

How to Backup Outlook Data Manually

There are many ways to backup your Outlook data. Some of them are manual methods where you can take backup of your PST or OST file without using an external software. Let’s start with the PST file first, then move onto the OST files.

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I. Backup PST Files (Direct Export)

Open Outlook → File tab

Select Open & Export → Import/Export

Choose Export to a file → Outlook Data File (.pst)

Select folders to backup (entire mailbox or specific folders)

Choose backup location (external drive recommended)

Enable "Include subfolders" and set password protection if needed

Pro Tip: Store backups in at least two physical locations (external HDD + cloud) for redundancy.

II. Backup OST Files (Conversion Required)

Since OST files sync with Exchange servers, you must first convert them to PST:

Using Outlook:

Create new PST via File > Account Settings > Data Files

Drag-drop OST content to new PST folder

Using Conversion Tools:

Tools like SysTools OST to PST Converter handle large/corrupted files

Preserves email metadata during conversion

How to Automate Outlook Backups

Another way to take backup of Outlook email client is to use automated tools that do it on a regular basis or opt for external software that significantly reduces your workload by doing it for you.

I. Built-In Automation Options

For Windows Users:

Create a scheduled task in Task Scheduler

Set trigger (daily/weekly)

Run Outlook with /cleanimportexport switch

For Mac Users:

Use Time Machine to backup entire Outlook profile

II. Top Third-Party Backup Tools

Search on the internet

Handle files over 50GB reliably

Automate cloud backups to Google Drive/Dropbox

Encrypt backups for security

Restoring Outlook Data from Backup

You have two sections here: One for PST and other for OST.

I. How to Restore PST Files

Open Outlook → File > Open & Export > Import/Export

Select Import from another program/file

Choose your backup PST file

Select destination folder (original or new)

Troubleshooting Tip: For corrupted PSTs, Microsoft's ScanPST.exe tool can repair minor issues. For severe corruption, tools like SysTools

PST Recovery Tool⁠

recover up to 98% of data from damaged files.

II. How to Restore OST Files

Convert backup OST to PST first

Import PST into Outlook

For Exchange accounts, let Outlook rebuild OST automatically

Best Practices for Reliable Backups

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Frequency Matters

Daily for heavy users

Weekly for casual users

Storage Strategy

Local (External SSD for speed)

Cloud (OneDrive/Google Drive for accessibility)

Security Measures

Password-protect PST files

Use AES-256 encryption for sensitive data

Maintenance

Compact PST files monthly (File > Account Settings > Data Files > Settings > Compact Now)

Keep backups under 20GB for stability

FAQs

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Q: Can I backup Outlook without PST files? A: Yes! Office 365 users can enable archive mailboxes or use Exchange Online Archiving.

Q: How to recover a corrupted PST file? A: First try Microsoft's ScanPST.exe. For severe cases, use specialized recovery tools.

Q: Does Outlook 365 automatically backup emails? A: No, but Exchange Online retains deleted items for 14-30 days (extendable via retention policies).

Q: What's the maximum PST file size? A: 50GB for Outlook 2016-2019, but performance degrades over 20GB.

Q: Can I access PST backups without Outlook? A: Yes, with free viewers like PST Viewer Pro or web-based converters.

Final Thoughts

Backing up Outlook isn't just IT's responsibility—it's yours. Whether you choose manual exports for occasional backups or invest in automation for business-critical data, the key is consistency.

Action Step Today:

Export your most important folder to PST

Store it on a USB drive

Set a calendar reminder to repeat monthly