I receive a login error when I login to the webacces, what could occur this issue?

When SELinux is enabled, this is blocking your connection from the webserver to the Zarafa server.

You may solve this by allowing Apache to make network connections:

setsebool httpd_can_network_connect=1

or by disabling SELinux altogether:

setenforce permissive

When you choose to disable SELinux, you will also want to edit /etc/sysconfig/selinux to disable it for reboots too.

Hints en Tips

More information about Selinux can be found here: http://fedora.redhat.com/docs/selinux-faq/