[exim] ESMTP smarthost

Hello all,

Today, I wanted to configure a new smarthost on Exim that allow us to
send mails with a bigger size.
The old smarthost use the port 25 without authentification and it
works perfectly.
The new one is an ESMTP server and I have to use the port 587.

So I modified, the exim config :
    dc_smarthost = 'smtp.some_host.fr::587'

And added the authentification parameters in the
/etc/exim/passwd.client, like this :

    'smtp.some_host.fr':login:password

But when I take a look to the log, I can see this :

Recipient address rejected: Missing Authentication


For the moment, I don't modified the configuration of my mail
client... So I continue to send mails with the port 25...

Is this possible, to send mail with the port 25 and Exim redirect them
to the smarthost on port 587 ?


Thanks in advance for you're reply.

Sebastien