I wrote another article - this one is a simple howto that explains a way to provide secure and non-secure webmail access through an Apache virtualhost.
Simple to set-up, probably takes between 5-15 minutes - just adds a .conf file into the /etc/httpd/confd./ folder (parsed by Apache).
Copy and paste tutorial written using CentOS - applicable to most distro's though.
Requires minimal coding and works well - according to Zimbra technician
Enjoy - please post any problems or feedback, so I can fine tune things.
Link is to the Wiki article directly.
The zimbra.conf file is also attached for direct download - for those who need no instructions