Question regarding fixing of "From/Sender Address"

[Abid Hussain]

Dear All,
I have a question regarding postfix configuration.

I have a mail server configured via postfix on centos. If an authorize user send email through command prompt he is able to change "from address/sender address" and can send email. I want to block this capability. i am explaining the problem point wise as below.

I have an authorized e-mail user by the name [email protected]
It logs on at mail server through console by providing his credentials (uesrname/password)
after authentication he create a mail and change sender address from [email protected] to [email protected] and sends the mail to another legitimate user [email protected]
In [email protected] inbox the mail appears to be came from [email protected] instead of actual sender [email protected]
Kindly advise how change of "fro/sender address" can be blocked.

Regards