Listing 1 xinetd configuration for qmail smtpd that invokes tcpd as a wrapper around qmail-smtpd

 # default: on
 # description: smtp for qmail.
 service smtp
 {
 disable = no
 flags = REUSE NAMEINARGS
 socket_type = stream
 protocol = tcp
 wait = no
 user = qmaild
 server = /usr/sbin/tcpd
 server_args = /var/qmail/bin/tcp-env _R \
 /var/qmail/bin/qmail-smtpd
 }

 (A similar configuration file can be used for qmail-pop3d, which is 
 qmail's built-in POP3 daemon.)