{HEAD ~ Incoming message packets} are intercepted and screened for {TAIL ~ readily discoverable characteristics} indicative of an infected message 
are intercepted for
{ HEAD ~ Incoming message packets } are intercepted and screened for { TAIL ~ readily discoverable characteristics } indicative of an infected message
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH