Invalid MailDirSize File error
If you getting a Invalid MailDirSize File error warning While trying to modify your mail box quota from cPanel, you just need to follow the steps below to solve this issue.
1. Log into cPanel
2. Click on File Manager
3. Click on the folder icon next to the mail folder
4. Click on the folder icon next to the domain name
5. Click on the folder icon next to the email user name
6. Click on the file called maildirsize in that folder (don’t click on the icon but the file’s name itself).
7. Right click your mouse and click to delete the file. Once you delete it, it will reform for the account automatically and it should then have the correct quota size.