Yes, that message display when I try to start apache inside my jail box.

 [Thu Jul 10 13:23:41 2008] [alert] mod_unique_id: unable to gethostbyname(”mailserver”)

To resolve this problem, just edit /etc/hosts

add record for ‘mailserver’ entry, like :

::1                     localhost localhost.my.domain
127.0.0.1               localhost localhost.my.domain
172.88.1.5              email.rasyid.com mailserver

Restart apache and test it yourself.