Removing Originial Sender IP from headers

==== Required information ====
- iRedMail version: 0.8.6
- Store mail accounts in MySQL
- Debain 7 64Bit
- Related log if you're reporting an issue:
====

hey guys I was wondering if anyone had any success writing  PCRE lines to remove the original IP/Agent/Name form the send, so that the chains on the headers starts at localhost 127.0.0.1 on the server rather than my Outlook Agent/IP

I know we will need to use in the postfix main.cf
smtp_header_checks = pcre:/path/to/file

but I am not sure what rules I need to put in.

NOTE: I currently use both DKIM and DomainKeys with iRedMail so we can not strip those please.

Thanks!