Can mail rules search for discrete words?

I have created a number of mail rules on the server in a crude attempt at stopping some of the spam we receive. However, it does not seem able to search for discrete words. For example, the word ‘cialis’ appears in ‘specialist’. Another example is where the word ‘cum’ appears in ‘cumbersome’. Therefore, any message with these letter sequences is caught by my mail rule. I have tried including a space on either side of the word. This does work. Is there a way that i can get the rules processor to search for discrete words?

Regards

Ian.