[TriLUG] Postfix question

[Chris Knowles]

What's the fastest/easiest way to reject all e-mail from a given e-mail
address in postfix?  I've been googling for 30 minutes and I'm no closer
to understanding this.

I don't want to block the entire domain, nor any other addresses (right
now).  There's just this one.  And if I could get the server to give
them back a message, that'd be great.

As always, thanks for the help.

CJK