1. A method for identifying linked electronic mails, the method comprising: receiving a query from a user, wherein the query comprises at least a segment of an electronic mail; based on the segment received, identifying linked electronic mails via rendering to the user at least one of related subsets or related supersets of electronic mails related to the received segment, wherein the related subsets and related supersets are threads of the segment received and arranged in hierarchy; said rendering comprising: detecting at least one match between a query root segment signature of one the received segment and a root segment signature index, the root segment signature index comprising at least one of a word index and a metadata index, wherein the word index comprises at least one of a keyword and, and wherein the metadata index comprises at least one of temporal information and navigation information; said detecting comprising: receiving a pre-defined token match threshold; identifying a set of root segment signatures of the root segment signature index; comparing the query root segment signature with each root segment signature of the set of root segment signatures of the root segment signature index; identifying a subset of the root segment signature index, wherein a match between the root segment signature and the query root segment signature is at least the pre-defined token match threshold; and building an electronic mail thread hierarchy based on the at least one detected match.