The machine with the mail spool took a long time to boot but did come back up and is now up and running with the new release which is Ubuntu 15.10.

     The machine that houses /home directories is still in progress.  I had to interrupt and re-start the upgrade which can end up with a lot of dpkg –configure -a incarnations before everything is finally current.  Not good to interrupt but had no choice as it hung during the os-prober.