The GroupWise 8 client runs great under Ubuntu, but there is a slight problem with the time zone. Because the GroupWise client is a Java based client, a slight adjustment may need to be made.
Java, for some reason, expects a symbolic link at /etc/localtime. When it doesn't get it, it defaults to, usually, the wrong time zone. This caused issues like the calendar in GroupWise to be off.
To fix this:
sudo cp /etc/localtime /etc/localtime.bak
sudo ln -s -f sudo ln -s -f /usr/share/zoneinfo/Your/Timezone /etc/localtime