Tools for processing email and other electronic messages should be abl
e to recognize and manipulate threads, that is, conversations among tw
o or more people carried out by exchange of messages. While user clien
ts typically insert in messages structural information useful for reco
vering threads, inconsistencies between clients, loose standards, crea
tive user behavior, and the subjective nature of conversation make thr
eading systems based on structural information only partially successf
ul. We propose that this situation is unlikely to change, and that thr
eading of electronic messages be treated as a language processing task
. Preliminary experiments show that a significant level of threading e
ffectiveness can be achieved by applying standard text matching method
s from information retrieval to the textual portions of messages. (C)
1997 Elsevier Science Ltd.