Exim causes server overload.

Sending out a newsletter (200,000+) always causes the server to over-
load. load average raises to 500 and there are more than 4000
processes (exim keeps creating process even if server is over-loaded).

We use a PHP script to send each e-mail individually. I don't know if
this is the most effective way. Would it be better to create files in
the mail queue? creating 200,000 files should not take more than one
hour, while running the PHP scripts takes several days.

thanks