Restrict 'senders' of mail to members of the own domain

[Frans Couwberghs]

Hi,

Can i force the SMTP server to 'outbound relay' only mail from members of the own domain?

I mean:
- suppose my domain is 'iks.com'
- a user sends a mail with a wrong sender address, eg with the command 'rcpt to:<someone@not-iks.com>
- the smtp server rejects the relay

Frans