Hi rabinca,
If you have a particular suspicious IP you can do a look-up here: http://www.botscout.com/search.htm
or here: http://www.senderbase.org/senderbase_queries/detailip?search_string= (give in particular IP)
But as always this could be looking for a needle in a haystack, see: http://www.robtex.com/dns/karmamendoza.com.ar.html#records
comes with a long …long blacklist,
polonus