{TAIL ~ a thread level} representing {HEAD ~ a response level} of each of the at least two e mail messages within the mail thread and inserted into a thread level field; and 
{ TAIL ~ a thread level } representing { HEAD ~ a response level } of each of the at least two e mail messages within the mail thread and inserted into a thread level field ; and
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH