I discovered a bug relating to PostOffices location. I had reconfigured my plesk using the Reconfigurator to have my PostOffices at D:\PostOffices. After patching it RESET the location to c:\Program Files\SWSoft\Plesk\Mail Servers\MailEnable\PostOffices\ BUT it did NOT put the files there. All I had to do was copy the PostOffices back to the original location and reconfigure to fix it. The error I was getting was "Unable to lock mailbox". FYI.