[exim] Queue problems and Optimize Exim

Hi,

I'm having a problem with my exim's queue, could somebody help me?

I have 10 process to resolve the queue, and i limit the number of emails
that i send to exim's queue, by PHP. This limit is 1000 emails.

But some emails still in exim's queue with none status, then my free slots
on my queue is down, until that my queue is full and my server down

How can i optimize the configuration of my exim and how can i do to
manipulate the queue?