How can I check my outlook mail quota usage?

You can check Outlook quota usage by using Outlook Web App or Microsoft Outlook.

Outlook Web App

1. Login Outlook Web App (https://staffmail.um.edu.mo)
2. Click the gear icon in the top-right corner, then click Options.
   
3. In account page, look for the Mailbox Usage.
   

Microsoft Outlook (Windows)

1. Click File tab and select Info in the left column.
2. In file menu, click Cleanup Tools, then select Mailbox Cleanup in the drop down box.
   
3. In Mailbox Cleanup window, click view mailbox size button.
   
4. In Folder Size window, click Sever Data tab.
   
5. The Server Data tab will display the mailbox usage and list the size of each folder.