Exchange 2010 - Content Filtering

I am wanting to block emails that contain "Hello!" by adding it to the "Anti-spam" - "Content Filtering" but it fails to work because of the special character ! is there anyway to get it to work?

I thought using the below guide would work but I have had no luck with it:-

http://technet.microsoft.com/en-us/library/aa997187%28v=exchg.141%29.aspx

Hopefully someone with a better understanding of the regular expressions can help me.