merging non redundant segments of {TAIL ~ the each} of the related e mail messages into a single message document by ordering the non redundant segments hierarchically by the response level and {HEAD ~ the mail timestamp} of the each of the related e mail messages 
merging non redundant segments of { TAIL ~ the each } of the related e mail messages into a single message document by ordering the non redundant segments hierarchically by the response level and { HEAD ~ the mail timestamp } of the each of the related e mail messages
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH