[Exim] misconfigured mail server

I got 448 of these over a two day period. When I noticed it, I
emailed the provider and blocked the specific ip address with
iptables. It took me two days to notice the problem because it
started late at night and I was away from my computers most of the
following day:

May 29 18:32:19 vife exim: 2003-05-29 18:32:19 rejected HELO
from [65.205.75.34]: syntactically invalid argument(s):
svr_nt40.pinnacle.com

So what does this mean, exactly?

Rossz