[Exim] Delivering all local mail via exim to another port

We are migrating exim slowly into a sendmail system

We plan on moving sendmail to another port, and putting exim on 25 and using
a manualrouter to redirect to port 2525

So far we have

domainlist relay_to_domains = @mx_primary
hostlist relay_from_hosts = 127.0.0.1 : lsearch:/var/log/pop_log
domainlist hosts_treat_as_local = self.domain.com
domainlist local_domains = self.domain.com

router :

send_to_sendmail:
        driver = manualroute
        domains = +relay_to_domains
        route_list = * $domain
        transport = remote_smtp_port
        self=pass
        no_more

Transport
remote_smtp_port:
        driver = smtp
        allow_localhost
        port = 2525

This just results in frozen messages
Lowest numbered MX record points to local host

I'm sure its one option I have missed, the final deliverys are going to a
sendmail system currently inplace so all we need to do atm is accept any
mail that the MX is primary on, and then pipe out to sendmail on port 2525
Thanks

Darren