dividing the mail thread into respective segments by analyzing the at least two thread body intervals of {HEAD ~ the thread body field} in the each of {TAIL ~ the related e mail messages} 
dividing the mail thread into respective segments by analyzing the at least two thread body intervals of { HEAD ~ the thread body field } in the each of { TAIL ~ the related e mail messages }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL