Sometimes an email account goes over quota and the quota can’t be adjusted due to the following error:
Error invalid maildir size file
The following commands ran as root will resolve most email quota issues for a Cpanel account, including incorrect quota calculations. Substitute <cpaneluser> with the Cpanel user which owns the email account having issues.
cd /home/<cpaneluser>/mail/ rm -f maildirsize /scripts/generate_maildirsize --confirm --allaccounts --verbose <cpaneluser> cd ../.cpanel rm -f email_accounts rm -f email_accounts*