[Exim] Sending messages to a gateway problem

Hello,

I would like to send all outgoing messages to a anti-virus gateway,
which listen on port 12345.
I have checked the FAQ and I have configured exim with send_to_gateway
instead of lookuphost. It works fine but all messages are redirected to
port 25, but not 12345.
I have tried :
send_to_gateway:
           driver = domainlist
           transport = remote_smtp
           route_list = "* mygw.my.domain:12345 byname"

and

send_to_gateway:
           driver = domainlist
           transport = remote_smtp
           route_list = "* mygw.my.domain 12345 byname"

It doesn't work...
Thanks for your help.

--
Jean-Baptiste Jacquemard
========================
J. POLLAK & Cie SNC
4, rue de la Bourse
75002 PARIS