how do I configure sendmail not to resolve IPs in the headers?

Hi,

I would like to disguise my internal name structure and have sendmail
use something like localhost or 192.168.3.15 in the headers like this
instead:

Received: from localhost (localhost.localdomain [192.168.1.1]) by
localhost (8.14.2/8.14.2) with ESMTP for ; Fri, 25
Jan 2008 14:00:00 +0100

Also I would like to be able to set the hostname presented during the
helo handshake

250 Hello [192.168.0.2], pleased to meet you

without disabling dns lookup in sendmail altogether.

Is that possible at all? Or at least in part?

Willy