[CentOS] restricting mails from "mail" command to specific domains only in postfix

Hi Friends,

I have configured Postfix mail server on Centos  for relaying mails
from 5 linux servers (including itself) within the same LAN. The
postfix mail server should relay mails from these 5 linux servers for
specific domains only. For example hosts 192.168.0.23/24/25/26/27 and
the postfix mail server should only be able to receive and send mails
from and to example.com,example2.com and example3.com domains only.
Below is the configuration of the postfix mail server

myhostname = test.example.com
myorigin = $mydomain
inet_interfaces = all
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
mynetworks_style = subnet
mynetworks = 192.168.0.23/32,192.168.0.24/32,192.168.0.25/32,127.0.0.1/32,192.168.0.26/32,192.168.0.27/32
,relay_domains = $mydestination,example.com,example2.com,example3.com
smtpd_recipient_restrictions =
reject_unauth_destination,permit_mynetworks,reject


The issue I am facing is that whenever things are working fine when I
check the things through telnet but when I do testing through command
line through "mail" command I am able to send mails to any domain from
these 5 servers.

bash-2.05$ telnet test.example.com 25
Trying 192.168.0.27...
Connected to test.
Escape character is '^]'.
220 test.example.com ESMTP Postfix (2.2.5)
mail from:ankush.grover at example.com
250 Ok
501 Syntax: RCPT TO: <address>
rcpt to:ankush at gmail.com
554 <ankush at gmail.com>: Relay access denied


How can I restrict mails even going through "mail" command from these
5 servers to specific domains only. These 5 servers are running some
cronjobs and these cronjobs output it mailed through "mail" command.


Regards

Ankush