sendmail header obscuring

hello,

I have lots of mail clients, with private IPs, sending mail through our mail server. In the header of each mail outgoing I can find something like

Received: from [127.0.0.1] ([192.168.0.9])
by linux-virtua1.localhost (8.13.8/8.13.8/SuSE Linux 0.8)
...

question is: is there any way to avoid the private IPs to appear in the header? I would like to substitute (or simply drop) any reference to my internal network structure.
Deleting HReceived in sendmail.cf doesn't work, because it deletes (better said: it does not write) the Received line also with inbound messages.

Thanks for your time.

Yes there is a number of ways.

One way is to modify HReceived in the sendmail configuration file (sendmail.cf)

For example, change:

    HReceived: $?sfrom $s $.$?_($?s$|from $.$_)

to something like the following:

    HReceived: $?sfrom my.net (mail.my.net [111.222.333.444])

For more information see the sendmail man page.

This works, unfortunately, both ways. That is, even inbound messages will have the Received header line changed in <mynet.com> etc.
I am trying to mask only the outbound mail.