email header contains IP address of sending client

[Martin Vegter]

When I send email via my Postfix, the header actually contains the IP
address of my laptop. Such as 192.168.1.113 [12.34.56.78]) in the
example below:

Received: from mail.origin.com (mail.origin.com [65.254.242.180])
        by mail.destination.com (Postfix) with ESMTPS id 31A1B66
        for <u...@destination.com>; Thu,  4 Dec 2014 21:00:36 +0100 (CET)
Received: from [192.168.1.113] (unknown [12.34.56.78])
        by mail.origin.com (Postfix) with ESMTPSA id 08AE908
        for <u...@destination.com>; Thu,  4 Dec 2014 21:00:36 +0100 (CET)

Is it possible to disable this, or would that constitute "breaking
standards" ?
Is there any use in exposing my laptop IP address?

PS: I understand that in the above example, 192.168.1.113 is a
non-routable IP. But it could be any IP, depending on the client.

thanks,
Martin