Listing 2 tcpd hosts.allow file that sets RELAYCLIENT for network

192.168.3 and then invokes qmail-smtpd

 #
 # hosts.allow This file describes the names of the hosts which are
 # allowed to use the local INET services, as decided
 # by the '/usr/sbin/tcpd' server.
 #

 tcp-env: 192.168.3.: setenv = RELAYCLIENT