smtp test returns syntax error

I have xymon 4.2.3 on solaris and running smtp test on several servers on a variety of platforms. All show 'green' status, smtp ok. However when I review the details I see the following:

501 5.5.2 Syntax error in parameters scanning ""

I am also using Big Brother to monitor while I transition to xymon. BB does not report the same syntax error.

Any ideas on how to troubleshoot this? I am simply using the keyword 'smtp' in my bb-hosts file on both BB and xymon.

Thanks in advance.

Bill