I could see the following errors:
# /usr/local/psa/bin/sw-engine-pleskrun /usr/local/psa/admin/plib/DailyMaintainance/script.php
2013-11-20T09:26:51+08:00 ERR (3) [panel]: Error during calculation disk usage for mailnames on service node local : Unable to calculate Maildir++ size: No such file or directory
System error 2: No such file or directory
or in the
Feb 14 13:23:01 server postfix/pipe: 9B616E13E6: to=, relay=plesk_virtual, delay=56829, delays=56828/0.64/0/0.16, dsn=4.3.0, status=deferred (temporary failure. Command output: ./Maildir: No such file or directory 4.2.1 Message can not be delivered at this time )
Maildir for the mail account was not created properly.
To fix the misconfiguration issue it is needed to run the