hi,
i have succefully installed zimbra5 rc2 on debian etch,
after some retry cause of dependencies failure:
the installer doesn't check all the missing libs,
here the apt-get
apt-get install sudo libidn11 curl fetchmail libgmp3c2 libxml2 openssl libltdl3 perl psmisc libexpat1 libpcre3
psmisc: killall command
libpcre3 : for postfix
libexpat1 : for aspell if i remember