How to Reduce a Large OneNote Notebook Storage Size

To reduce a large OneNote notebook storage size, use the correct account, product, permissions, and destination. This guide explains the supported workflow and the checks that confirm the result.

Identify the Message, Account, and Destination

Confirm the owning account, required permissions, affected files or services, and the exact outcome you need. Keep a backup when the task changes local content or removes access.

Quick Outlook Workflow

First, select Save & Backup. Next, select Optimize All Files Now, and verify the final state before changing any backup or secondary account.

How to Reduce a Large OneNote Notebook Storage Size

1. Select Save & Backup
2. Select Optimize All Files Now
3. Open File Explorer
4. Open Microsoft > OneNote > 16.0 > Backup

After the final step, reopen the affected app, portal, file, or account page and confirm the exact status or behavior described in the title.

Use WPS Office for Related Work While Resolving This Microsoft Issue

WPS Office does not replace the Outlook or Exchange mailbox control required for reducing a large OneNote notebook storage size. Complete the mailbox, delivery, account, or server action in Outlook or the Microsoft 365 portal.

While you work on reducing a large OneNote notebook storage size, WPS Office provides a free Microsoft Office-compatible workspace through Writer, Spreadsheets, Presentation, and PDF. It opens and saves common DOCX, XLSX, PPTX, and PDF files in a familiar interface, so related local work can continue without waiting for the Microsoft-side issue to be fixed.

For work related to reducing a large OneNote notebook storage size, WPS AI can assist with drafting and rewriting in Writer, formulas and data insights in Spreadsheets, editable slide creation in Presentation, and summaries or document questions in PDF.

Test advanced macros, add-ins, external connections, sensitivity controls, and Microsoft-only cloud integrations on a copy before moving a critical workflow. WPS AI availability and usage limits can vary by plan, platform, region, and app version.

Practical Checks That Prevent a Repeat

• Record which account, app, and file owns the workflow
• Keep a verified backup before removing access, changing ownership, or replacing a local file
• Apply high-impact changes to one test item or user before expanding the scope
• Save confirmation numbers, dates, and screenshots of the final settings when they affect billing, security, or permissions

Frequently Asked Questions

Why should I select Save & Backup?

Select Save & Backup. The available Send to OneNote behavior depends on Outlook and OneNote versions. Test one message first, then confirm whether each selected email creates a page or combines content.

What should I check after I select Optimize All Files Now?

Verify sender, recipients, sent date, subject, body, attachments, and the destination notebook or section. Confirm the account type, product version, ownership, and permissions before assuming the control is unavailable.

What result should I expect after I open File Explorer?

Not every Outlook voting or actionable-message workflow prevents a later change. The sender must use the capabilities supported by that message type or form. Keep the relevant backup or confirmation until you have checked the result.

How can I confirm that the steps to reduce a large OneNote notebook storage size worked?

Open Microsoft > OneNote > 16.0 > Backup. Reopen the affected app or portal and confirm that the expected status persists.