1. Login to the cPanel for your hosting package, commonly found at http://www.yourdomainname.com/cpanel (yourdomainname.com should be replaced with your actual domain name)
2. Click on the Email Accounts module in cPanel.
3. On the resulting page click the Change Quota icon to the right of the email address you want to modify. A drop down box allowing you change your quota will show up, as seen in the image below.
4. Set the new quota then click Change Quota to save your changes.
Did this work for you? If not, let us know what trouble you had in the MacHighway Forums.