- Mailbox shows the incorrect size in Plesk UI that differs from the size of the directory
- The file
/var/qmail/mailnames/example.com/jdoe/Maildir/maildirsizecontains wrong data about the size of the mailbox
- Mailbox directory
/var/qmail/mailnames/example.com/jdoe/Maildircontains one or several folders started with ".INBOX"
Invalid mailbox subfolders. Mailbox contains several ".INBOX" folders resulted in Dovecot calculating disk usage several times.
Rename INBOX folders in the mail client.