I installed the Release 6.0.4_GA_2038.DEBIAN5 DEBIAN5 FOSS edition with the domain zimbra.geismar.com (the machine hostname) but want set my users as user@geismar.com instead of user@zimbra.geismar.com.

I created a new domain geismar.com but when I create a new user the default domain is set to zimbra.geismar.com. I can change to geismar.com but how to set geismar.com as the default ?

Thanks in advance for your help.