Bill, I was the guy doing the upgrade for Philippe
It's the first time (and I did upgrade quite a lot) that it happened to me.
OTOH, it's the first "dual server" setup I upgrade (mta/ldap on one server, mailstore on the other).
Philippe, I now remember we had an error/warning while upgrading the mailstore server about the ssl.crt and ssl.key... Could you please check in the upgrade log (and maybe attach the log to the support case) ?