While installing latest Parallels Plesk version (9.0), noticed an unusual option :) :

Different mailservers
16. (*) Qmail mailserver
17. ( ) Postfix mailserver

Could this be true, that Parallels finally decided to drop Qmail?
Now don't get me wrong, but qmail wasn't updated for 10 years already, and any additional feature requires a patch...
And.. did you ever try to read qmail's logs? :)