Sorry, there is another thing I had to do in order for the update check to work, in the crontab for the zimbra user, I updated the cronjob like so (on redhat I did
crontab -e -u zimbra).
Code:
#
# Check zimbraVersionCheckURL for new update.
# Only runs if this server matches zimbraVersionCheckServer
#
30 2 * * * /opt/zimbra/libexec/zmcheckversion -m >> /dev/null 2>&1
Notice the -m, running the update check without that argument just displays the help, you need to tell it to actually do the check.
Let me know if that helps any.