[1] Diff: rfc2821.txt - rfc5321.txt (2008-10-12 00:43:47 +09:00 版) <http://tools.ietf.org/rfcdiff?url1=http://www.ietf.org/rfc/rfc2821.txt&url2=http://www.ietf.org/rfc/rfc5321.txt> (名無しさん)