modify received headers in exim for one IP only

hi,

Like a lot of us, i send emails from my cellphone. When i send an email ( using outlook mobile), i use my own smtp server, but my cellphone providers gateway IP appears in the received headers...
see:

I want to change the 216.198.139.38 to 127.0.0.1 everytime it appears in the received headers...

The problem with 216.198.139.98 is that they are on a lot of blacklists... and my mails are sometimes dropped, or tagged as spam...

i'm sure some of you have the solution near you
Some guy like Chirpy should know the solution ... ?

thanks a lot for your help!

 

I've found that code... this is the way to go.. but i need a bit of help ...

Code:

  received_header_text = Received: \
      ${if def:sender_rcvhost {from ${if def:authenticated_id \
      {127.0.0.1 (helo=authenticated.user-IP.removed)} \
      {$sender_rcvhost }}\n\t}}\
      by $primary_hostname \
      ${if def:received_protocol {with $received_protocol}} \
      ${if def:tls_cipher {($tls_cipher)\n\t}}\
      (Exim $version_number)\n\t\
      id $message_id\
      ${if def:received_for {\n\tfor $received_for}}

First, is there any received_* that is not included in this code that should be included ?
I'm asking because this is rewriting the received_header.... everything that was previously inserted will be deleted.

Second, if i want this to work only for one ip, what should i change ?
I know it's in the two or three first lines... but these regex and stuff are hard hehe!

third, where do i put this ??? exim configuration is splitted in many files...