それっぽいpatchがいくつかあったので当ててみたんですが、 220 hogehoge.com ESMTP EHLO [192.168.4.11] 250-hogehoge.com 250-AUTH LOGIN CRAM-MD5 PLAIN 250-AUTH=LOGIN CRAM-MD5 PLAIN 250-PIPELINING 250 8BITMIME AUTH LOGIN 503 auth not available (#5.3.3) 503 auth not available (#5.3.3) RSET 250 flushed MAIL FROM:<yama@kawa.com> 250 ok RCPT TO:<inu@neko.com> 553 sorry, that domain isn't in my list of allowed rcpthosts (#5.7.1) QUIT 221 hogehoge.com