Very often I see this in syslog:
check-quota filter[XXXXX]: Some args not defined. Use /opt/psa/handlers/hooks/check-quota <CONTEXT> <FROM> <TO>
Is there something to be fixed about that?
The message is just a warning, which may be caused by a problem with some mail handler.
You may either ignore it or try recreating mail handlers as per instructions in this article:
113664 How to recreate mail handlers in Parallels Plesk Panel 10.4 and above