Sometime our cPanel user account can get over quota which might cause webmail to stop working. cPanel user can free up disk usage by deleting unwanted data or upgrading the hosting package so that it can have more free space.
Sometime on performing these two action, user might still not be able to access webmail and showing following error message:
“User is Over Quota” or “Internal Server Error 500”
On such occasion the server admin needs to manually remove cPanel overquota file.
What you have to do is remove cpanels overquota file manually. Let’s say that user “domain1” is having issue described above.
root@server [~]# cd /var/cpanel/overquota/
root@server [/var/cpanel/overquota]# ls
./ ../ domain1 domain2 domain3 domain4
root@server [/var/cpanel/overquota]# rm domain1
After you deleted the file located at /var/cpanel/overquota/domain1, webmail should start to work again.