Download Shared Folders in Outlook: Step-by-Step PST Guide

Struggling to access your team’s shared inbox during a flight or meeting without internet? Or looking for a reliable way to back up shared mailbox emails into a local pst file? If you’ve ever searched for how to download shared folders in Outlook, you’re not alone. Most users face this issue when they need offline access to critical shared resources or want to create a permanent archive of a team’s communications. The confusion often stems from a fundamental misunderstanding: Outlook doesn’t have a single "Download" button that magically saves everything to your desktop. Instead, it uses a system of caching and exporting that works in very different ways depending on your goals.

In my 15 years working with enterprise email systems, I’ve seen this exact question come up in three distinct contexts. Sometimes, a user just wants the shared calendar to work offline. Other times, an IT admin needs to stop the shared mailbox from bloating everyone’s hard drives. And occasionally, a team is migrating data and needs to export those shared emails into a standalone backup file. This guide will walk you through the mechanisms behind these actions, distinguish between temporary caching and permanent exporting, and give you the specific steps to achieve what you actually need, whether you’re using the classic desktop client or the newer web-based interfaces.

Understanding How Outlook Handles Shared Data

To navigate this topic effectively, you first need to grasp how Outlook treats data that doesn’t belong to you personally. When you add a shared mailbox to your profile, Outlook doesn’t just "look" at the server every time you click an email; it creates a local shadow copy of that data. This is the core of Cached Exchange Mode.

Cached Exchange Mode vs. Online-Only Access

Think of Cached Exchange Mode like a mirror. When you open a shared folder, Outlook creates an "offline folder" copy of that data on your local hard drive, stored within a file called .ost (Offline Storage Table). This is crucial for performance. If your shared mailbox is hosted in the Microsoft 365 cloud, reading emails directly from the server every time you click would be painfully slow. Instead, Outlook reads from the local .ost file, which is nearly instantaneous.

It is vital to distinguish between "caching" and "exporting." When you enable caching, you are allowing Outlook to keep a working copy for speed. This is dynamic; it syncs back and forth with the server. When you "export" to a PST file, you are creating a static snapshot. A PST file is a standalone container that can be moved, opened on other computers, and used for long-term archiving. Caching is for using the data now; exporting is for saving the data forever.

I’ve often seen users conflate these two. They think if they check a box to "download" shared folders, they are creating a backup. They aren’t. They are just enabling the offline mirror. If you delete that mirror, your data isn’t gone; it’s still on the server. But if you delete a PST file, that backup is gone forever (unless you have another backup). For commercial or operational use, you choose offline copies for speed and connectivity resilience. You choose PST exports for data retention and migration.

Impact on OST File Size and Performance

Here is where it gets tricky for many organizations. Because caching shared folders dumps their contents into your local .ost file, a busy shared inbox can devour your disk space and slow down Outlook. I recall a case where a small support team was sharing a single mailbox. That mailbox received 50,000 emails per year with average file sizes of roughly 200KB each. That’s nearly 10GB of data. Multiply that by five team members, and suddenly everyone’s hard drive is filling up, and Outlook is grinding to a halt during sync.

Modern Outlook versions, starting with 2016, include a feature called "Download email for the past," often represented as a slider. This prevents the .ost file from becoming a digital landfill. By default, it usually limits the amount of mail held locally to a few months. However, if you have a high-volume shared site mailbox or a support queue, even that limit can feel generous. If you find your laptop sluggish, this is often the culprit: the local cache for shared folders is too large. Understanding this balance is the first step before you decide whether to tweak the settings or export the data entirely.

Step-by-Step: Save Shared Mailbox to PST

So, what if you don’t just want the speed of a cached copy? What if you need to save shared mailbox to pst outlook for backup or migration purposes? This is a manual process that requires specific permissions and steps.

Method 1: Using the Export/Import Wizard (Classic Outlook)

For the classic desktop version of Outlook (the one most enterprise users still rely on), the built-in tool is the Export Import Wizard. This is the only native way to move shared emails into a standalone file.

Here is how I typically guide clients through this process:

1. Open the Wizard: Go to File > Open & Export > Import/Export.
2. Select the Action: Choose "Export to a file" and select "Outlook Data File (.pst)."
3. Choose the Source: In the next window, you must select the shared mailbox from the left-hand tree, not just your personal mailbox. Click Next.
4. Define the Scope: You can choose to export just the Inbox or "Entire Mailbox." I recommend "Entire Mailbox" if you are doing a full backup. Ensure "Include subfolders" is checked.
5. Save the File: Choose a destination folder on your hard drive (e.g., C:\Backups\SharedTeam_PST). Give it a clear name.
6. Complete: Click Finish. You will be asked to create a password. For a local backup, you can usually leave this blank.

Once this is done, you have a portable PST file. You can open it, copy it to a USB drive, or move it to a new computer. A critical limitation to note: this is a one-time snapshot. If a new email arrives in the shared inbox tomorrow, it won’t appear in this PST file until you run the export again. It is not a live sync.

Method 2: Outlook Web App (OWA) Workarounds

What if you don’t have access to the desktop client? The Outlook Web App (OWA) has significantly fewer export options. You will not find a "Save to PST" button here.

For calendars, the workaround is often sufficient. If you need to download shared calendar from outlook web app, you can export it as an .ics file. Navigate to the shared calendar, click the calendar name at the top, select "Calendar settings" (or the gear icon), and look for the "Import & Export" section. You can export the data to a CSV file or subscribe to the calendar.

For email, OWA is more restrictive. You cannot easily save a shared mailbox to a PST file directly from the browser. If you strictly require a PST file, your best bet in OWA is to select the emails you need and print them to a PDF, or use a third-party browser extension or service that can convert emails to a file format. However, for bulk data, I always recommend using the desktop client for the most reliable export experience.

Advanced: Managing Offline Access via Registry & GPO

For IT administrators and power users, the "Download shared folders" setting is often managed under the hood by registry keys. This is where you have precise control over whether Outlook caches shared mail, caches only non-mail folders (like calendars), or ignores shared folders entirely. This is highly relevant when you need to export shared folder data outlook users can access, or when you need to stop that access to save bandwidth.

Configuring CacheOthersMail and DownloadSharedFolders

There are two primary registry values that control this behavior. It is important to know that changing these requires a restart of Outlook.

1. CacheOthersMail This value determines whether mail folders are cached.

• Value 1 (Default): Caches both mail and non-mail folders. This is the standard "full offline access" mode.
• Value 0: Caches only non-mail folders (Calendar, Tasks, Contacts). Mail folders are accessed online only. This is useful if you want your shared team calendar to work offline but don’t want the heavy shared email inbox taking up disk space.

2. DownloadSharedFolders This value is a master switch for all shared folders.

• Value 1 (Default): Shared folders are downloaded/cached.
• Value 0: No shared folders are cached. Everything must be accessed online. This is the "zero disk footprint" mode.

Here are the registry paths you need to know. For standard user-level changes, you look here: HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Cached Mode

For organization-wide enforcement, you look here: HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\16.0\Outlook\Cached Mode

Note the difference: the Policies path overrides the standard path and applies to all profiles on the machine. This is why IT admins use the second path. If you are troubleshooting why a user "can’t" download shared folders, it is likely because a policy key is overriding their local preference.

Deploying Settings via Group Policy

For enterprises, manually editing the registry on every user’s laptop is not scalable. Instead, we use Group Policy Objects (GPO) with the outlk16.admx template.

Here is how I deploy this:

1. Open the Group Policy Management Console.
2. Navigate to User Configuration > Administrative Templates.
3. Expand your version of Microsoft Outlook (e.g., Outlook 2016).
4. Expand Outlook Options > Delegates.
5. Look for the policy Disable shared mail folder caching.
   • Disabled: Reverts to default (caches mail and non-mail).
   • Enabled: Caches non-mail folders only.

If you need to disable all shared folder caching, you look under Account Settings > Exchange > Cached Exchange Mode and find the policy Download shared non-mail folders. Setting this to "Enabled" effectively tells Outlook to ignore shared folders in the cache entirely.

After configuring the GPO, run gpupdate /force on the client to push the changes. I’ve found that checking the registry key on the user’s machine after the update is the only way to be 100% sure the setting has taken effect, as GPO replication can sometimes be laggy.

Troubleshooting Common Download Issues

Even with the right settings, things break. The most common issue I diagnose is a permissions problem. Users assume that if they can see the shared mailbox in the list, they have the rights to download it. This is not always true.

Why Can't I See My Shared Folder Locally?

If you are in Cached Exchange Mode but the shared folders appear "Online" or "Unavailable" when you disconnect, check mailbox permissions.

• Full Delegation vs. Full Access: Ensure the user has "Full Access" permission to the shared mailbox. This grants read and write privileges.
• Send on Behalf: This is a separate permission for sending email. It does not automatically grant the ability to read the inbox unless "Full Access" is also granted.
• Verify Caching: Go to File > Account Settings > Account Settings. Double-click the shared mailbox account. Go to the More Settings > Advanced tab. Ensure the "Download shared folders" checkbox is actually checked. If it is unchecked, Outlook will never create the local copy, regardless of your other settings.

I recommend creating a simple checklist for users:

1. Do you have Full Access rights? (Ask your admin).
2. Is "Download shared folders" checked in Account Settings?
3. Is your computer connected to the internet at least once to sync the initial data?

Fixing Sync Errors and Disappearing Folders

A popular question I see in support forums is: "Why can't I download my shared mailbox to PST?"

Usually, the error is not actually a download issue but a permissions or client issue. If the export wizard fails or creates an empty file, it is often because the user selected the parent folder of the shared mailbox rather than the shared mailbox itself in the "Select Folder" step.

Another common headache is the .ost file itself becoming corrupted. If your shared folders disappear or Outlook hangs when opening them, it is likely the local cache is damaged. You can repair this by closing Outlook and running the inrst utility (found in the Outlook folder, usually named Outlaw.exe or similar, or by deleting the .ost file and letting Outlook rebuild it). Deleting the .ost is safe; it will just re-download the data from the server, so ensure you are connected to the internet before you do this.

New Outlook vs. Classic: What's Different?

This is the area that causes the most confusion right now. Microsoft is pushing "New Outlook for Windows" hard, but it is not a feature-for-feature replacement yet.

Feature Availability in New Outlook for Windows

In my experience with beta testing the new client, the handling of shared mailboxes is different.

For offline access, the New Outlook does cache shared folders, but the control over how much is cached (the slider) is less visible in the UI compared to the classic "Download email for the past" setting. If you are a heavy user of shared resources and rely on offline access, I would stick with Classic Outlook until Microsoft fully matures the offline caching features in the new client.

Frequently Asked Questions

What does downloading shared folders do in Outlook? It creates a local copy of the shared mailbox data in your .ost file. This enables offline access and faster retrieval of emails and calendars, but it increases your local disk space usage.

Does downloading a shared folder delete the original emails? No. The "download" process is a caching mechanism. It does not delete the original emails from the server. Deleting an item from your local offline copy may just mark it for deletion on the server upon sync, or it may just remove it from the local view, depending on your specific settings. The data is safe on the server unless explicitly deleted from the source.

Can I download shared calendars from Outlook Web App? Yes. You can export shared calendars as .ics files or subscribe to them from the web interface. However, you cannot save the entire mailbox to a PST file directly from OWA. For full email export, you need the desktop client.

Why can't I download my shared mailbox to PST? This is usually due to one of two reasons:

1. Permissions: You do not have "Full Access" permissions to the shared mailbox.
2. Client Limitation: You are using New Outlook or OWA, which have limited export capabilities. Ensure you are using Classic Outlook and that you have the correct administrative rights.

Conclusion

We have covered a lot of ground, from the basic mechanics of caching to the complex world of registry keys. To summarize the three main approaches:

1. UI Export: Use the Export Import Wizard in Classic Outlook to create a permanent PST file for backup or migration.
2. Registry/GPO: Use CacheOthersMail and DownloadSharedFolders keys for enterprise-level control over offline access and disk usage.
3. OWA/Basic Access: Use the web app for simple calendar exports or when full offline email access is not required.

The eternal trade-off here is between offline availability and disk footprint. The more you download and cache, the faster your work becomes when you are offline, but the more space you consume and the higher the risk of .ost file bloat.

I hope this clarifies the landscape for you. If you are still facing specific issues—like your shared folder refusing to sync or your PST file coming up empty—please leave a comment with your specific Outlook version. Different versions handle these quirks slightly differently. Also, if you are dealing with a massive .ost file, be sure to check our guide on "Managing Large OST Files" for optimization tips that go beyond just deleting shared folders.