denying user@ip senders

[NERvOus]

I'd like to forbid this:

mail from: [EMAIL PROTECTED]
250 ok
rcpt to: [EMAIL PROTECTED]
250 ok

I don't want ppl to be able to send mail as [EMAIL PROTECTED] and force them
to use [EMAIL PROTECTED] instead, even if the recipient is a local user.
How can I achieve it?

Regards.
-- 
NERvOus, di nome e di fatto. ([EMAIL PROTECTED] || [EMAIL PROTECTED])
ICQ UIN: 2618261 || #nervous @ irc.jnet.it