[qmailtoaster] smtp auth

[Erol KAHRAMAN]

hi,
How i can prevent a user to send mail  on behalf of an other user in the same domain. I will try to explain in example;
I have a domain named " test.com". There are two users named xxx and yyy. If i am a bad gay i can do this;

# telnet smtp_server_ip 25
mail from: [EMAIL PROTECTED]
250 ok
rcpt to: [EMAIL PROTECTED]
250 ok
data
354 go ahead
you are kicked out!!!
.
250 ok 1139401722 qp 10908

So i wrote the email on behalf of xxx user to yyy user. If i am able to smtp auth in the same domain this problem will not occure.
How i can solve this problem ?

--
Erol KAHRAMAN
System Network Administrator