Check your mailbox storage usage


Target audience: Entire McGill community

This article shows how to check the amount of mailbox storage you have used and how much space remains.

Student mailboxes on Office 365 (Exchange Online) have 20 GB of storage space. Faculty and staff mailboxes have 100 GB.

In this article:

Follow the steps below to configure your Windows 10 device.

Important: McGill Outlook email storage capacity reduction starting May 31st 2024


On May 31st, 2024, McGill’s Outlook email storage for all students will be reduced to 20GB to comply with Microsoft’s new Storage quota for its educational sector clients. The Outlook email storage provided to staff or faculty members will not be affected.

If you are a McGill student, please verify your current storage using the present article.

If your current storage exceeds 20GB, start by emptying your mailbox’s deleted items. As a secondary step, go through your inbox and all its online storage folders and download any "big" attachments such as videos, PowerPoint presentations or images by saving them to another location using the Save as... option in the attachment drop-down menu and then by Removing them.

Please note: these options are only available on Outlook for PC, not on the online or Mac versions. If you only use these platforms, download the attachments then save/delete the email. (Don't forget to empty the deleted items folder after.)

If you plan on storing those files on OneDrive, be aware that OneDrive's storage will also be adjusted to 20GB starting May 31st. For more information: consult the IT Services announcement on the subject.

Check your mailbox usage from Outlook on the web (OWA)

  1. Sign into the Office 365 Outlook Web App at
  2. Click on the Settings gear icon in the upper right corner of the window and select View all Outlook settings, at the bottom of that pane.

    View all Outlook settings

  3. From the left side panel, click General settings and select Storage.

    Storage used

  4. The screen will show how much space has been used out of the total mailbox size, as well as how much space is being used per folder.

View folder sizes and empty contents from specific folders

On the Storage screen, you may wish to free up some space by deleting messages you no longer need from specific folders.

  1. Click the Empty dropdown list next to the folder name and select the messages you want to delete: All, 3 months and older, 6 months and older, or 12 months and older.

    Empty folder contents

  2. You are asked to confirm before the items are permanently deleted.

    Delete warning

Filter your emails on whether they contain attachments and order by size or date

  1. Sign into the Office 365 Outlook Web App at
  2. In the Inbox or any other folder, Click on the filter icon then, from the drop-down menu, select Has files to filter on emails that have attachments. You can also use the Sort submenu to order the emails by date or by size.

Check your mailbox usage from the Outlook application

  1. Click the File menu and select Info if it is not already selected.
  2. On the Account Information screen, under  Mailbox Settings, you will see how much space you have remaining in your Exchange mailbox.

    Outlook mailbox storage

    You can choose to clean up your mailbox using the Tools provided.
    Outlook Mailbox Cleanup