[Exim] Two questions on reject log...

Lo everyone,

2002-10-29 07:37:45 rejected EHLO from [61.72.146.115]: syntactically
invalid argument(s): \300\374\305\302\301\370
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2002-10-29 07:37:45 rejected HELO from [61.72.146.115]: syntactically
invalid argument(s): \300\374\305\302\301\370


Is this, some kind of DoS attempt? If not, what should be causing this??

Secondly,

2002-10-28 02:36:19 recipient <SAVAGE@???> refused from
(om40.yourmailsource.com) [216.177.60.45]
sender=<NOLIST-1064843966-5933-SAVAGE**SAVAGE*ZA*ORG@???
> (failed to find host name from IP address)

What causes this?? Failed to find host name from IP Address? Is it missing
reverse DNS?