If you get Error – invalid maildirsize file when attempting to change the quota for an email account, here's a simple solution that will fix this problem.

  1. Connect to your site via FTP.
  2. Navigate to the following path /mail/yourdomain.com/user
    replace with your real domain & user name
  3. From this directory, delete the file named maildirsize
  4. Once this file is deleted, cPanel will automatically recreate this file with proper values. You might have to wait for email activity for this to happen. You will also have to refresh your cPanel page.


If the correct mailbox quota is still not being displayed, from within cPanel, you can navigate to email accounts and click the change quota button to set a new quota.