To setup dbmail-imapd to run under xinetd you need to the following:
On CentOS 4.3: Create file: /etc/xinetd.d/dbmail-imapd File contents should look like:
service imap { socket_type = stream wait = no user = root server = /usr/local/sbin/dbmail-imapd protocol = tcp server_args = -n log_on_failure += USERID disable = no }
Modify the path to the server as needed.
Thats it!.