Depending on your needs and situation, you might need to increase or
decrease your email quota.
Increasing the email quota will allow user
to store more emails before being forced to delete the mails or empty
the trash folder.
1) Login to cPanel by accessing the URL http://domainname/cpanel/
2) Click on Email Accounts
under “Mail” tab
3) Search for the Email that you wish to change the quota for.
4) Then choose on the selected Email Account -> Change Quota
and specify the value that you wish to change and click on Change Quota