Hello Melvyn, 
The Global Spam Rule that Zach was referencing is in the ( system settings -> security -> Antispam Administration -> Custom Rules ). 
Using this you can do a RegEx scan ( see image below ) and assign a SPAM weight to the message. 
Please let me know if you have any questions on this. Thank you
Tony
 
								Tony Scholz
System/Network Administrator
SmarterTools Inc.
www.smartertools.com