Reynald Affeldt Naoki Kobayashi Formalization and Verification of a Mail Server in Coq. 217-233 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2609&spage=217 2002 conf/isss2/2002 ISSS db/conf/isss2/isss2002.html#AffeldtK02