appending {HEAD ~ e mail identification data} into {TAIL ~ a header} of the mail thread of the at least two e mail messages when transmitted, wherein the e mail identification data includes at least: 
into
appending { HEAD ~ e mail identification data } into { TAIL ~ a header } of the mail thread of the at least two e mail messages when transmitted , wherein the e mail identification data includes at least :
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL 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 OTH OTH