Safely and effectively managing storage in your M365 account

Managing Outlook and OneDrive storage

Regular mailbox and cloud storage maintenance helps ensure continued access to email, files, and collaborative tools across Microsoft 365. This article explains how to check, reduce, and manage storage usage in Outlook (Exchange), OneDrive, and Teams to prevent delivery issues and maintain performance.

Applicable to: Fort Collins, Pueblo, Spur, System
Affiliation: Students, Faculty, Staff, Guests

Prerequisites

You must be able to sign in to your CSU Microsoft 365 account and access Outlook (Exchange), OneDrive, and Teams before following these steps.

1. Manage Exchange (Outlook) storage

Important: Both your Inbox and Archive folders count toward your total mailbox quota.

Check your mailbox size

Go to your account settings and open the Storage Usage tab to review mailbox size.
In Outlook on the web, navigate to Settings → General → Storage to view usage.
In the Outlook desktop app, open File → Tools → Mailbox Cleanup → View Mailbox Size.
Sort messages by size or date to find large or older emails for cleanup.
Use search filters to locate messages with large attachments or specific keywords (e.g., hasattachments:true).

Delete emails

Select unnecessary messages and click the Delete button.
Empty the Deleted Items folder periodically by right-clicking and selecting Empty Folder.
Save important attachments externally to OneDrive, SharePoint, or departmental shared storage.
Avoid using the Archive folder for long-term storage.

Move items to a PST file (advanced)

Create a PST (Personal Storage Table) file stored locally or on a network drive.
Move selected emails into the PST file to reduce mailbox quota usage.
Consult with your local IT experts for guidance.
Note: Emails moved to a PST file no longer count against your mailbox quota as they are now saved on your local device.

Recover deleted emails

Check the Deleted Items folder first. If the email is there, right-click and choose Move → Inbox or another folder.
Recover permanently deleted emails using the Recover Deleted Itemsfeature:
- In Outlook desktop, go to the Folder and click Recover Deleted Items.
- In Outlook on the web (OWA), open the Deleted Items folder and click Recover items deleted from this folder.
Select the items you want to restore and click Restore. Recovered messages will return to the Deleted Itemsfolder.
- Note: Items in the Recoverable Items folder are retained for up to 30 days, depending on your organization's retention policy. After this period, they are permanently deleted and cannot be recovered.

Retention and quota policy

Deleted Items are cleared after CSU’s retention period (typically 30 days).
Recoverable Items are held briefly before permanent removal.
When your mailbox reaches its quota, new messages cannot be sent or received.

Tip: Perform regular mailbox cleanups to maintain performance and stay within CSU storage limits.

2. Manage OneDrive storage

Review and organize files

Open OneDrive Settings → Manage Storage.
Organize files into folders.
Delete unnecessary files by right-clicking and selecting Delete.

Free up space

Move large or infrequently used files to departmental shared storage or another approved location.
See the M365 Storage Project for alternatives to personal OneDrive storage.
Enable Files On-Demand to store only frequently used files locally.
Compress large files before uploading.

Recover deleted files

Access the Recycle Bin to restore files within the retention period (30 days).

Important: Files purged from the Recycle Bin cannot be recovered.

3. Manage Teams storage

Review and delete files

Access the Files tab in Teams or channels.
Delete unnecessary files and recordings.

Best practices

Save important files to OneDrive or SharePoint.
Clean up chats by deleting old conversations or shared files.

4. General M365 storage tips

Best practices

Review shared documents, recordings, and content in SharePoint.
Back up critical data externally.
Understand retention and quota policies.

Actions that make items unrecoverable

Exceeding quotas: May result in data purge or inaccessibility.
Retention expirations: Data is permanently deleted after policy period.
Manual deletions: Items purged from Recoverable Items or Recycle Bin cannot be recovered.
Overwriting files: May result in loss without recovery.

Separating personal and university information

Maintaining a clear boundary between personal and university-related data ensures compliance, security, and ease of management.

Why it’s important

Data security: Mixing personal data increases breach risk.
Ownership clarity: University accounts are subject to audits.
Efficiency: Easier access to university-related content.

Best practices

Store personal files in a separate personal OneDrive or cloud account.
Use a personal email for non-university communication.
Create distinct folders for university projects.
Review shared documents for personal info.

Risks of mixing data

Loss of access: M365 accounts may be deactivated upon departure.
Policy violations: May result in restricted access or disciplinary action.

See solution article for further guidance.

Best practices

Perform weekly reviews of email, OneDrive, and Teams.
Conduct monthly deep cleans.
Carry out quarterly audits.
Leverage shared storage like SharePoint.
Use compression and external drives for archiving.

Outcome

By following these steps, you can efficiently manage storage across your M365 account, prevent clutter, and ensure critical files and communications are secure and accessible. For additional support, contact the IT Service Desk.