[exim] Exim4 | Modify headers

Hy there.

I hope you can give me some help on this one. I am kind of stuck and can't find
an appropiate answer. Exim4 is installed with the split configuration.

I want to modify the recieved_header_text, to anonyminize it as much as
possible.

1.) I managed to modify the recieved_header_text = in 02_exim4-config_options
as

received_header_text = Received: \
${if def:sender_rcvhost {from 127.0.0.1\n\t}\
{${if def:sender_ident \
{from ${quote_local_part:$sender_ident} }}\
${if def:sender_helo_name {(helo=127.0.0.3)\n\t}}}}\
by $primary_hostname \
${if def:received_protocol {with $received_protocol}} \
${if def:tls_cipher {($tls_cipher)\n\t}}\
(Exim latest)\n\t\
${if def:sender_address \
{(envelope-from <$sender_address>)\n\t}}\
id $message_exim_id\
${if def:received_for {\n\tfor $received_for}}


2.) So now the mail source looks like this

Return-path: <user@???>
Envelope-to: user_2@???
Delivery-date: Sat, 03 Aug 2013 10:53:00 +0200
Received: from 127.0.0.1
    by server500gb.chello.at with esmtpsa (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32)
    (Exim latest)
    (envelope-from <user@???>)
    id 1V5XZy-0004Bp-VG
    for user_2@???; Sat, 03 Aug 2013 10:53:00 +0200
 From: user <user@???>
To: user_2@???
Date: Sat, 03 Aug 2013 10:52:32 +0200
Message-ID: <3081037.y7q8ZU0DAf@kubuntuisiert>
User-Agent: KMail/4.8.5 (Linux/3.2.0-51-generic; KDE/4.8.5; x86_64; ; )
MIME-Version: 1.0
Content-Type: multipart/signed; boundary="nextPart137562676.tHzCL3Ggym"; 
micalg="pgp-sha1";      protocol="application/pgp-signature"
Content-Transfer-Encoding: 7Bit
X-SA-Exim-Connect-IP: 192.168.2.35
X-SA-Exim-Mail-From: user@???
X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on
    server500gb.chello.at
X-Spam-Level: 
X-Spam-Status: No, score=-1.0 required=5.0 tests=ALL_TRUSTED,TVD_RCVD_IP,
    TVD_RCVD_IP4,URIBL_BLOCKED autolearn=ham version=3.3.2
 Subject: Headertext
X-SA-Exim-Version: 4.2.1 (built Sun, 08 Jan 2012 03:05:19 +0000)
X-SA-Exim-Scanned: Yes (on server500gb.chello.at)

--nextPart137562676.tHzCL3Ggym
Content-Transfer-Encoding: 7Bit
Content-Type: text/plain; charset="us-ascii"




3.) I want to modify three strings

a.) User-Agent to something like Windows NT 4.0 blaablaablaa

b.) X-SA-EXIM-Connect-IP to 127.0.0.1

c.) Message-ID I would like to modify the hostname to something like myhost



I would appreciate your help :D
Thank you in advance!