[exim] reject-log questions

Hi

I thought, I understood most of exims logs, but now I found 2 stange
entries:

2004-09-15 17:56:42 H=januXXXde [134XXX10] F=<keXXXsb@???> rejected
RCPT <mail@???>: Sender verify failed
2004-09-15 21:34:58 rejected HELO from [62XXX41]: syntactically invalid
argument(s): nt_49613199.intern.XXX.de

The XXX parts are replacements from me to hide some clients information.

Can someone explain me those two lines?

Regards,
Steffen