[exim] default ratelimit

Hello all,

I have the following snippet running in acl_check_rcpt, which limits
authenticated users to a number of messages per hour:

   warn    authenticated = *
           ratelimit = ${lookup mysql{Q_RATELIMIT}} / 1h / strict / 
$authenticated_id
           log_message = Authenticated sender rate $authenticated_id 
$authenticated_sender $sender_rate / $sender_rate_period

   deny    authenticated = *
           ratelimit = ${lookup mysql{Q_RATELIMIT}} / 1h / strict / 
$authenticated_id
           log_message = Authenticated sender rate $authenticated_id 
$authenticated_sender $sender_rate / $sender_rate_period

   accept  authenticated = *
           control       = submission/sender_retain

The problem is that the above code seems to set a per_host limit too,
even though I didn't specify such a thing.
I have one user who sent 2 messages in an hour and yet it triggered the
deny above.
His gateway IP is used by multiple users, hence my hunch that exim
actually limits the client IP too ?

Is such a thing possible ?