exim dying on slink

[drew@penguin.ipunet.com]

I've recently installed a system with Slink, and set it up as
a mail hub for our domain.  We also run a type of mailing list
from another box, which our mail hub acts as a smarthost for.

However, when the mailing list sends out email (anywhere from
1-2 thousand at once), after a number of successful deliveries,
the mail hub stops accepting connections on port 25.

In order to send any more, I have to kill -HUP inetd.

Here's the smtp line in /etc/inetd.conf:
smtp	stream	tcp	nowait	mail	/usr/sbin/exim exim -bs


Anybody know what I can do to correct this problem,  other than 
slowing down how fast the mailing list sends out email?

--Andrew