[Exim] relay error with spam reporting (spamcop)

I have a setup where mail comes in on port 25 to exim, does virus filtering
and basic checks

The redirects to the domain but on a different port and makes a smtp
connection to the existing sendmail config (We are migrating but its highly
customised so its not cut and dry hence this method)

This has been fine for months but now we are getting blacklisted for sending
spam, whats happening is spam is coming in, exim accepts and redirects to
another port, users are reporting to spamcop etc.. spamcop filters the
headers and blames our main IP as the sender.

Is there a way to mangle the headers so this doesnt happen?

example :-

Received: from uk-server2.carpediem-it.co.uk (uk-server2.carpediem-it.co.uk
[193.111.226.41]) by uk-server2.carpediem-it.co.uk (8.12.10) with ESMTP id
i1LAYAPv022300 sender admin@??? for <darren@???>;
Sat, 21 Feb 2004 02:34:10 -0800
Received: from c2bapps19.btconnect.com ([193.113.154.35]
helo=dswu231.btconnect.com)
by uk-server2.carpediem-it.co.uk with smtp (Exim 4.30)
id 1AuUSY-0005nQ-9A