Your Outlook mailbox is full and you cannot send or receive new emails. This happens when your Microsoft 365 mailbox reaches its 50 GB storage limit. The primary cause is the accumulation of old emails and large attachments over time. This article explains how to use the Archive feature to move old items out of your main mailbox and free up space.
You will learn the steps to manually archive items and how to set up AutoArchive for automatic cleanup. We will also cover where archived files are stored and how to access them later.
Key Takeaways: Managing Your 50 GB Mailbox Limit
- File > Info > Tools > Clean Up Old Items: Manually runs the Archive tool to move old emails to a local archive file based on age.
- File > Options > Advanced > AutoArchive Settings: Configures Outlook to automatically move or delete old items on a schedule you set.
- Ctrl+Shift+A: Opens the Archive dialog box to quickly archive selected folders or items without using the ribbon.
Why Your Mailbox Hits the 50 GB Limit and How Archive Helps
Microsoft 365 business plans typically include a 50 GB limit for your primary Exchange Online mailbox. This space is for your active emails, calendar items, contacts, and tasks. The limit is not for your entire account but specifically for the live data synced with the server.
When you reach this limit, you will get a warning and eventually be blocked from sending new messages. Receiving new mail may also fail. The Archive feature in Outlook provides a solution by moving older, less frequently used items out of this live mailbox.
Archiving creates a separate local file on your computer with a .pst extension. Items in this archive file are removed from the server, freeing up your 50 GB quota. You can still open and search the archive file from within Outlook, but the data is stored on your local machine or a network drive.
Understanding Archive vs. Delete and Online Archive
Archiving is different from deleting. Deleted items go to the Deleted Items folder and are permanently removed after a retention period. Archived items are preserved in a separate data file you control. This is ideal for compliance or keeping a complete record.
Do not confuse the local Archive (.pst file) with the Microsoft 365 Online Archive (an additional mailbox with its own storage). This article covers the local Archive tool, which is available in all Outlook versions and does not require a specific license.
Steps to Manually Archive Old Mailbox Items
Use this method for an immediate, one-time cleanup of old emails and other items. You choose which folders to archive and how old the items must be.
- Open the Archive Dialog
In Outlook, go to the File tab. Select Info from the left menu. Click the Tools button, then choose Clean Up Old Items. You can also press Ctrl+Shift+A from the main mailbox view. - Set the Archive Date and Folder
The Archive dialog box opens. The top option archives all folders according to their AutoArchive settings. To archive a specific folder, select the second option: Archive this folder and all subfolders. Then click the folder you want to process, such as Inbox. - Choose an Archive Date
In the Archive items older than field, select a date. For example, choose a date from three years ago. Outlook will archive all items in the selected folder received before that date. - Select the Archive File Location
Click the Browse button to choose where to save the archive file. It is best to save it to a location with enough space, like your Documents folder or a network drive. You can use an existing .pst file or create a new one. Click OK to start the archive process. - Verify the Archive Completed
Outlook will move the items. You will see a new folder in your folder pane called Archive or with the name of your .pst file. Your main mailbox folders should now contain fewer items, freeing up space on the server.
How to Configure AutoArchive for Automatic Cleanup
Set up AutoArchive to have Outlook automatically move old items on a schedule, such as every 14 days. This prevents your mailbox from filling up again.
- Access AutoArchive Settings
Go to File > Options. Select the Advanced tab from the left sidebar. In the AutoArchive section, click the AutoArchive Settings button. - Configure Global AutoArchive Rules
In the AutoArchive dialog, check the box for Run AutoArchive every [X] days. Set the number of days, like 14. Choose whether to be prompted before running. Select the default action, such as Move old items to archive file. Set the default age for old items, such as 6 months. Click Apply to These Folders to set these as the default for all folders. - Set Individual Folder Policies
In your folder list, right-click a specific folder like Sent Items and choose Properties. Go to the AutoArchive tab. Here you can override the global settings. Choose Archive this folder using these settings and set a different age limit or action. You can also select Do not archive items in this folder for critical folders. - Run AutoArchive Now to Test
To run the AutoArchive process immediately with your new settings, go back to File > Info > Tools > Clean Up Old Items. In the dialog, select the first option: Archive all folders according to their AutoArchive settings. Click OK. Check the archive file to confirm items were moved correctly.
Common Mistakes and Limitations When Archiving
Archived Items Are Not Searchable from Outlook on the Web
Items moved to a local .pst archive file are only accessible on the computer where the file is stored. They will not appear in Outlook on the web or on the Outlook mobile app. If you need access from multiple devices, consider using the Microsoft 365 Online Archive feature instead, if available in your plan.
Archive File Becomes Too Large or Corrupt
The .pst file has its own size limit, which is 50 GB for newer Unicode formats. Storing a very large archive file on a slow drive can make Outlook sluggish when you access it. Regularly check the file size and consider creating multiple archive files by year. Use the Outlook Inbox Repair Tool (scanpst.exe) if the archive file fails to open.
Forgetting the Archive File Location or Password
If you move computers or reinstall Outlook, you must manually re-add the archive .pst file via File > Account Settings > Account Settings > Data Files tab. If you set a password on the archive file and forget it, Microsoft cannot recover it. Keep a record of the file location and any passwords in a secure place.
Local Archive vs. Online Archive vs. Deletion
| Item | Local Archive (.pst file) | Microsoft 365 Online Archive | Permanent Deletion |
|---|---|---|---|
| Primary Purpose | Free up primary mailbox space by moving items to local storage | Provide unlimited or additional cloud-based archive storage | Permanently remove items to comply with data policies |
| Storage Location | Your computer or network drive | Microsoft cloud servers | Items are removed from all locations |
| Accessibility | Only from Outlook on the PC with the file | From Outlook desktop, web, and mobile apps | Items cannot be accessed |
| Impact on 50 GB Mailbox | Immediately reduces mailbox size | Immediately reduces mailbox size | Immediately reduces mailbox size |
| License Requirement | None, available in all Outlook versions | Requires specific Microsoft 365 plan with Online Archive | None |
| Automation | Via AutoArchive settings | Via retention policies set by admin | Via Deleted Items retention policy |
You can now manage your 50 GB mailbox limit by moving old emails to an archive file. Use the manual archive for immediate cleanup or set up AutoArchive to prevent future issues. Remember that archived items are stored locally, so back up your .pst file. For a more advanced setup, explore creating multiple archive files organized by year or project. Use the Search Folders feature in Outlook to quickly find items across both your main mailbox and open archive files.