Hi George,
Actually, Qmail has not been updated for a few past years as it was so good when the last version 1.03 was released. Can you please PM me with your ticket number so I could check what happened there.
The ticket # is 828591.
They (Plesk support I guess) upgraded my Plesk to 8.4. LP support says I should be all set. I made a cursory check of my web sites and all seems to be good. I have Ruby on Rails installed on one of them but I havent had a chance to check that one out. It is for development purposes so I'm not too concerned about that one right now.
I still don't know what happened to cause the problem to begin with. Especially if what you say about qmail not being update in years is true.
Based on past experience, LP support reacted very quickly on this issue and it appears the solution is of very high quality. They recognized an issue with Plesk and did not hesitate to turn it over to Plesk support. Good job LP support!
George