Classification features include the position of messages in threads and the heuristics that were shown to correlate with requests or non-requests in our previous work (Korkontzelos and Ananiadou, 2014).
the heuristics are the following three observation and their combinations 3 : -the prefix "RE:" or "Re:" in the message subject -the occurrence of one or more question marks in the message body -the occurrence of question words, such as what, when and where in the message body Nouns, Adjectives, Verbs 68.0% Table 6: Evaluation results for the single-label setting.