220 itmedia.hoge.org ESMTP Postfix EHLO localhost ←「EHLO localhost」と入力 250-itmedia.hoge.org 250-PIPELINING 250-SIZE 10240000 250-ETRN 250- AUTH PLAIN LOGIN DIGEST-MD5 CRAM-MD5 ←これを確認 250 8BITMIME QUIT .