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