The email quota is an option on cPanel that allows you to change the disk space limit of your email account. To update the quota for an email account:
1. Log into your cPanel
2. Navigate to the EMAIL section and select Email Accounts
3. Scroll down to the email address for which you want to adjust the quota resources and click on MANAGE
4. Change the quota in the section STORAGE > Allocated Storage Space
5. Click on "UPDATE EMAIL SETTING" to save the changes.