Mozilla/5.0 (compatible; Yahoo! Slurp;http://help.yahoo.com/help/us/ysearch/slurp) Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; aggregator VocusBot 0.4; +http://www.vocus.com/vnhs.html) ----- (Aside: That Yahoo UA is also malformed; no space after second semi-colon.)
Odd, that. If I'd had any slurp hits from a non-yahoo IP I would have logged and blocked it, but I have nothing in the 63.232/16 range at all. It's possible the other UA got through but I suspect other fields would have trapped that as well.
I've added the IP plus the words aggregator, VocusBot and the .com to my blocklist. Thanks.